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< script > ! function ( ) { function t ( t ) { document . documentElement . setAttribute ( "data-theme" , t ) } var e = function ( ) { try { return new URLSearchParams ( window . location . search ) . get ( "docusaurus-theme" ) } catch ( t ) { } } ( ) || function ( ) { try { return localStorage . getItem ( "theme" ) } catch ( t ) { } } ( ) ; t ( null !== e ? e : "light" ) } ( ) , function ( ) { try { const c = new URLSearchParams ( window . location . search ) . entries ( ) ; for ( var [ t , e ] of c ) if ( t . startsWith ( "docusaurus-data-" ) ) { var a = t . replace ( "docusaurus-data-" , "data-" ) ; document . documentElement . setAttribute ( a , e ) } } catch ( t ) { } } ( ) < / script > < div id = "__docusaurus" > < div role = "region" aria-label = "Skip to main content" > < a class = "skipToContent_fXgn" href = "#__docusaurus_skipToContent_fallback" > Skip to main content< / a > < / div > < nav aria-label = "Main" class = "navbar navbar--fixed-top" > < div class = "navbar__inner" > < div class = "navbar__items" > < button aria-label = "Toggle navigation bar" aria-expanded = "false" class = "navbar__toggle clean-btn" type = "button" > < svg width = "30" height = "30" viewBox = "0 0 30 30" aria-hidden = "true" > < path stroke = "currentColor" stroke-linecap = "round" stroke-miterlimit = "10" stroke-width = "2" d = "M4 7h22M4 15h22M4 23h22" > < / path > < / svg > < / button > < a class = "navbar__brand" href = "/" > < div class = "navbar__logo" > < img src = "https://user-images.githubusercontent.com/10379601/29446482-04f7036a-841f-11e7-9872-91d1fc2ea683.png" alt = "Puppeteer Logo" class = "themedComponent_mlkZ themedComponent--light_NVdE" > < img src = "https://user-images.githubusercontent.com/10379601/29446482-04f7036a-841f-11e7-9872-91d1fc2ea683.png" alt = "Puppeteer Logo" class = "themedComponent_mlkZ themedComponent--dark_xIcU" > < / div > < b class = "navbar__title text--truncate" > Puppeteer< / b > < / a > < a aria-current = "page" class = "navbar__item navbar__link navbar__link--active" href = "/" > Docs< / a > < a class = "navbar__item navbar__link" href = "/api/puppeteer.puppeteernode" > Puppeteer API< / a > < a class = "navbar__item navbar__link" href = "/browsers-api/" > @puppeteer/browsers API< / a > < / div > < div class = "navbar__items navbar__items--right" > < div class = "navbar__item dropdown dropdown--hoverable dropdown--right" > < a class = "navbar__link" aria-haspopup = "true" aria-expanded = "false" role = "button" href = "/" > 21.9.0< / a > < ul class = "dropdown__menu" > < li > < a class = "dropdown__link" href = "/next/guides/debugging" > Next< / a > < / li > < li > < a aria-current = "page" class = "dropdown__link dropdown__link--active" href = "/guides/debugging" > 21.9.0< / a > < / li > < li > < hr class = "dropdown-separator" > < / li > < li class = "dropdown-archived-versions" > < b > Archived versions< / b > < / li > < li > < a href = "https://github.com/puppeteer/puppeteer/blob/puppeteer-v21.8.0/docs/api/index.md" target = "_blank" rel = "noopener noreferrer" class = "dropdown__link" > 21.8.0< svg width = "12" height = "12" aria-hidden = "true" viewBox = "0 0 24 24" class = "iconExternalLink_nPIU" > < path fill = "currentColor" d = "M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z" > < / path > < / svg > < / a > < / li > < li > < a href = "https://github.com/puppeteer/puppeteer/blob/puppeteer-v21.7.0/docs/api/index.md" target = "_blank" rel = "noopener noreferrer" class = "dropdown__link" > 21.7.0< svg width = "12" height = "12" aria-hidden = "true" viewBox = "0 0 24 24" class = "iconExternalLink_nPIU" > < path fill = "currentColor" d = "M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z" > < / path > < / svg > < / a > < / li > < li > < a href = "https://github.com/puppeteer/puppeteer/blob/puppeteer-v21.6.1/docs/api/index.md" target = "_blank" rel = "noopener noreferrer" class = "dropdown__link" > 21.6.1< svg width = "12" height = "12" aria-hidden = "true" viewBox = "0 0 24 24" class = "iconExternalLink_nPIU" > < path fill = "currentColor" d = "M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10.988l4.035 4-6.977 7.07 2.828 2.828 6.977-7.07 4.125 4.172v-11z" > < / path > < / svg > < / a > < / li > < li > < a href = "https://github.com/puppeteer/puppeteer/blob/puppeteer-v21.6.0/docs/api/index.md" target = "_blank" rel = "noopener noreferrer" class = "dropdown__link" > 21.6.0< svg width = "12" height = "12" aria-hidden = "true" viewBox = "0 0 24 24" class = "iconExternalLink_nPIU" > < path fill = "currentColor" d = "M21 13v10h-21v-19h12v2h-10v15h17v-8h2zm3-12h-10 . 988l4 . 035 4-6 . 977 7 . 0
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< p > Debugging with Puppeteer can be an arduous task. There is no < em > single< / em > method for
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debugging all possible issues since Puppeteer touches many distinct components
of a browser such as network requests and Web APIs. On a high note, Puppeteer
provides < em > several< / em > methods for debugging which hopefully does cover all possible
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issues.< / p >
< h2 class = "anchor anchorWithStickyNavbar_LWe7" id = "background" > Background< a href = "#background" class = "hash-link" aria-label = "Direct link to Background" title = "Direct link to Background" > < / a > < / h2 >
< p > In general, there are two possible sources of an issue: Code running on Node.js
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(which we call < em > server code< / em > ), and
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< a href = "/api/puppeteer.page.evaluate" > code running in the browser< / a >
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(which we call < em > client code< / em > ). There is also a third possible source being the
browser itself (which we call < em > internal code< / em > ), but if you suspect this is the
source < strong > after attempting the methods below< / strong > , we suggest
< a href = "https://github.com/puppeteer/puppeteer/issues" target = "_blank" rel = "noopener noreferrer" > searching existing issues< / a >
before
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< a href = "https://github.com/puppeteer/puppeteer/issues/new/choose" target = "_blank" rel = "noopener noreferrer" > filing an issue< / a > .< / p >
< h2 class = "anchor anchorWithStickyNavbar_LWe7" id = "debugging-methods-for-all-situations" > Debugging methods for all situations< a href = "#debugging-methods-for-all-situations" class = "hash-link" aria-label = "Direct link to Debugging methods for all situations" title = "Direct link to Debugging methods for all situations" > < / a > < / h2 >
< p > These methods can be used to debug any situation. These should be used as a
quick sanity check before diving into more complex methods.< / p >
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "turn-off-headless" > Turn off < a href = "/api/puppeteer.browserlaunchargumentoptions" > < code > headless< / code > < / a > < a href = "#turn-off-headless" class = "hash-link" aria-label = "Direct link to turn-off-headless" title = "Direct link to turn-off-headless" > < / a > < / h3 >
< p > Sometimes it' s useful to see what the browser is displaying. Instead of
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launching in
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< a href = "/api/puppeteer.browserlaunchargumentoptions" > < code > headless< / code > < / a > mode,
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launch a full version of the browser with
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< a href = "/api/puppeteer.browserlaunchargumentoptions" > < code > headless< / code > < / a > set to
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< code > false< / code > :< / p >
< div class = "language-ts codeBlockContainer_Ckt0 theme-code-block" style = "--prism-color:#393A34;--prism-background-color:#f6f8fa" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-ts codeBlock_bY9V thin-scrollbar" style = "color:#393A34;background-color:#f6f8fa" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:#393A34" > < span class = "token keyword" style = "color:#00009f" > const< / span > < span class = "token plain" > browser < / span > < span class = "token operator" style = "color:#393A34" > =< / span > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:#00009f" > await< / span > < span class = "token plain" > puppeteer< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > launch< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token punctuation" style = "color:#393A34" > {< / span > < span class = "token plain" > headless< / span > < span class = "token operator" style = "color:#393A34" > :< / span > < span class = "token plain" > < / span > < span class = "token boolean" style = "color:#36acaa" > false< / span > < span class = "token punctuation" style = "color:#393A34" > }< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_LjdS" > < path fill = "currentColor" d = "M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z" > < / path > < / svg > < / span > < / button > < / div > < / div > < / div >
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "puppeteer-slow-mo" > Puppeteer " slow-mo" < a href = "#puppeteer-slow-mo" class = "hash-link" aria-label = "Direct link to Puppeteer "slow-mo"" title = "Direct link to Puppeteer "slow-mo"" > < / a > < / h3 >
< p > The < a href = "/api/puppeteer.browserconnectoptions" > < code > slowMo< / code > < / a > option slows down
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Puppeteer operations by a specified amount of milliseconds. It' s another way to
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help see what' s going on.< / p >
< div class = "language-ts codeBlockContainer_Ckt0 theme-code-block" style = "--prism-color:#393A34;--prism-background-color:#f6f8fa" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-ts codeBlock_bY9V thin-scrollbar" style = "color:#393A34;background-color:#f6f8fa" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:#393A34" > < span class = "token keyword" style = "color:#00009f" > const< / span > < span class = "token plain" > browser < / span > < span class = "token operator" style = "color:#393A34" > =< / span > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:#00009f" > await< / span > < span class = "token plain" > puppeteer< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > launch< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token punctuation" style = "color:#393A34" > {< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > headless< / span > < span class = "token operator" style = "color:#393A34" > :< / span > < span class = "token plain" > < / span > < span class = "token boolean" style = "color:#36acaa" > false< / span > < span class = "token punctuation" style = "color:#393A34" > ,< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > slowMo< / span > < span class = "token operator" style = "color:#393A34" > :< / span > < span class = "token plain" > < / span > < span class = "token number" style = "color:#36acaa" > 250< / span > < span class = "token punctuation" style = "color:#393A34" > ,< / span > < span class = "token plain" > < / span > < span class = "token comment" style = "color:#999988;font-style:italic" > // slow down by 250ms< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:#393A34" > }< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_LjdS" > < path fill = "currentColor" d = "M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z" > < / path > < / svg > < / span > < / button > < / div > < / div > < / div >
< h2 class = "anchor anchorWithStickyNavbar_LWe7" id = "debugging-methods-for-client-code" > Debugging methods for client code< a href = "#debugging-methods-for-client-code" class = "hash-link" aria-label = "Direct link to Debugging methods for client code" title = "Direct link to Debugging methods for client code" > < / a > < / h2 >
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "capture-console-output" > Capture < code > console.*< / code > output< a href = "#capture-console-output" class = "hash-link" aria-label = "Direct link to capture-console-output" title = "Direct link to capture-console-output" > < / a > < / h3 >
< p > Since client code runs in the browser, doing < code > console.*< / code > in client code will not
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directly log to Node.js. However, you can < a href = "/api/puppeteer.page" > listen (page.on)< / a > for
the < a href = "/api/puppeteer.pageevents" > < code > console< / code > < / a > event which returns a
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payload with the logged text.< / p >
< div class = "language-ts codeBlockContainer_Ckt0 theme-code-block" style = "--prism-color:#393A34;--prism-background-color:#f6f8fa" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-ts codeBlock_bY9V thin-scrollbar" style = "color:#393A34;background-color:#f6f8fa" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > page< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > on< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token string" style = "color:#e3116c" > ' console' < / span > < span class = "token punctuation" style = "color:#393A34" > ,< / span > < span class = "token plain" > msg < / span > < span class = "token operator" style = "color:#393A34" > => < / span > < span class = "token plain" > < / span > < span class = "token builtin" > console< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > log< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token string" style = "color:#e3116c" > ' PAGE LOG:' < / span > < span class = "token punctuation" style = "color:#393A34" > ,< / span > < span class = "token plain" > msg< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > text< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:#00009f" > await< / span > < span class = "token plain" > page< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > evaluate< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token plain" > < / span > < span class = "token operator" style = "color:#393A34" > => < / span > < span class = "token plain" > < / span > < span class = "token builtin" > console< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > log< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token template-string template-punctuation string" style = "color:#e3116c" > `< / span > < span class = "token template-string string" style = "color:#e3116c" > url is < / span > < span class = "token template-string interpolation interpolation-punctuation punctuation" style = "color:#393A34" > ${< / span > < span class = "token template-string interpolation" > location< / span > < span class = "token template-string interpolation punctuation" style = "color:#393A34" > .< / span > < span class = "token template-string interpolation" > href< / span > < span class = "token template-string interpolation interpolation-punctuation punctuation" style = "color:#393A34" > }< / span > < span class = "token template-string template-punctuation string" style = "color:#e3116c" > `< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "use-the-debugger-in-the-browser" > Use the debugger in the browser< a href = "#use-the-debugger-in-the-browser" class = "hash-link" aria-label = "Direct link to Use the debugger in the browser" title = "Direct link to Use the debugger in the browser" > < / a > < / h3 >
< ol >
< li >
< p > Set < a href = "/api/puppeteer.browserlaunchargumentoptions" > < code > devtools< / code > < / a > to
< code > true< / code > when launching Puppeteer:< / p >
< div class = "language-ts codeBlockContainer_Ckt0 theme-code-block" style = "--prism-color:#393A34;--prism-background-color:#f6f8fa" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-ts codeBlock_bY9V thin-scrollbar" style = "color:#393A34;background-color:#f6f8fa" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:#393A34" > < span class = "token keyword" style = "color:#00009f" > const< / span > < span class = "token plain" > browser < / span > < span class = "token operator" style = "color:#393A34" > =< / span > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:#00009f" > await< / span > < span class = "token plain" > puppeteer< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > launch< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token punctuation" style = "color:#393A34" > {< / span > < span class = "token plain" > devtools< / span > < span class = "token operator" style = "color:#393A34" > :< / span > < span class = "token plain" > < / span > < span class = "token boolean" style = "color:#36acaa" > true< / span > < span class = "token punctuation" style = "color:#393A34" > }< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_LjdS" > < path fill = "currentColor" d = "M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z" > < / path > < / svg > < / span > < / button > < / div > < / div > < / div >
< / li >
< li >
< p > Add < code > debugger< / code > inside any client code you want debugged. For example,< / p >
< div class = "language-ts codeBlockContainer_Ckt0 theme-code-block" style = "--prism-color:#393A34;--prism-background-color:#f6f8fa" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-ts codeBlock_bY9V thin-scrollbar" style = "color:#393A34;background-color:#f6f8fa" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:#393A34" > < span class = "token keyword" style = "color:#00009f" > await< / span > < span class = "token plain" > page< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > evaluate< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token plain" > < / span > < span class = "token operator" style = "color:#393A34" > => < / span > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:#393A34" > {< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:#00009f" > debugger< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token punctuation" style = "color:#393A34" > }< / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_LjdS" > < path fill = "currentColor" d = "M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z" > < / path > < / svg > < / span > < / button > < / div > < / div > < / div >
< p > The Browser will now stop in the location the < code > debugger< / code > word is found in
debug mode.< / p >
< / li >
< / ol >
< h2 class = "anchor anchorWithStickyNavbar_LWe7" id = "debugging-methods-for-server-code" > Debugging methods for server code< a href = "#debugging-methods-for-server-code" class = "hash-link" aria-label = "Direct link to Debugging methods for server code" title = "Direct link to Debugging methods for server code" > < / a > < / h2 >
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "use-the-debugger-in-nodejs-chromechromium-only" > Use the debugger in Node.js (Chrome/Chromium-only)< a href = "#use-the-debugger-in-nodejs-chromechromium-only" class = "hash-link" aria-label = "Direct link to Use the debugger in Node.js (Chrome/Chromium-only)" title = "Direct link to Use the debugger in Node.js (Chrome/Chromium-only)" > < / a > < / h3 >
< p > Since server code intermingles with client code, this method of debugging is
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closely tied with the browser. For example, you can step over
< code > await page.click()< / code > in the server script and see the click happen in the
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browser.< / p >
< p > Note that you won' t be able to run < code > await page.click()< / code > in DevTools console due
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to this
< a href = "https://bugs.chromium.org/p/chromium/issues/detail?id=833928" target = "_blank" rel = "noopener noreferrer" > Chromium bug< / a > , so
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if you want to try something out, you have to add it to your test file.< / p >
< ol >
< li >
< p > Set < a href = "/api/puppeteer.browserlaunchargumentoptions" > < code > headless< / code > < / a > to
< code > false< / code > .< / p >
< / li >
< li >
< p > Add < code > debugger< / code > to any server code you want debugged. For example,< / p >
< div class = "language-ts codeBlockContainer_Ckt0 theme-code-block" style = "--prism-color:#393A34;--prism-background-color:#f6f8fa" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-ts codeBlock_bY9V thin-scrollbar" style = "color:#393A34;background-color:#f6f8fa" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:#393A34" > < span class = "token keyword" style = "color:#00009f" > debugger< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token keyword" style = "color:#00009f" > await< / span > < span class = "token plain" > page< / span > < span class = "token punctuation" style = "color:#393A34" > .< / span > < span class = "token function" style = "color:#d73a49" > click< / span > < span class = "token punctuation" style = "color:#393A34" > (< / span > < span class = "token string" style = "color:#e3116c" > ' a[target=_blank]' < / span > < span class = "token punctuation" style = "color:#393A34" > )< / span > < span class = "token punctuation" style = "color:#393A34" > ;< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_LjdS" > < path fill = "currentColor" d = "M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z" > < / path > < / svg > < / span > < / button > < / div > < / div > < / div >
< / li >
< li >
< p > Run your server code with < code > --inspect-brk< / code > . For example,< / p >
< div class = "language-bash codeBlockContainer_Ckt0 theme-code-block" style = "--prism-color:#393A34;--prism-background-color:#f6f8fa" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-bash codeBlock_bY9V thin-scrollbar" style = "color:#393A34;background-color:#f6f8fa" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:#393A34" > < span class = "token function" style = "color:#d73a49" > node< / span > < span class = "token plain" > --inspect-brk path/to/script.js< / span > < br > < / span > < / code > < / pre > < div class = "buttonGroup__atx" > < button type = "button" aria-label = "Copy code to clipboard" title = "Copy" class = "clean-btn" > < span class = "copyButtonIcons_eSgA" aria-hidden = "true" > < svg viewBox = "0 0 24 24" class = "copyButtonIcon_y97N" > < path fill = "currentColor" d = "M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z" > < / path > < / svg > < svg viewBox = "0 0 24 24" class = "copyButtonSuccessIcon_LjdS" > < path fill = "currentColor" d = "M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z" > < / path > < / svg > < / span > < / button > < / div > < / div > < / div >
< / li >
< li >
< p > In the opened Chrome/Chromium browser, open < code > chrome://inspect/#devices< / code > and
click < code > inspect< / code > .< / p >
< / li >
< li >
< p > In the newly opened test browser, press < code > F8< / code > to resume test execution.< / p >
< / li >
< li >
< p > Now your < code > debugger< / code > statement will be hit and you can debug in the test
browser.< / p >
< / li >
< / ol >
< h3 class = "anchor anchorWithStickyNavbar_LWe7" id = "log-devtools-protocol-traffic" > Log DevTools protocol traffic< a href = "#log-devtools-protocol-traffic" class = "hash-link" aria-label = "Direct link to Log DevTools protocol traffic" title = "Direct link to Log DevTools protocol traffic" > < / a > < / h3 >
< p > If all else fails, it' s possible there may be an issue between Puppeteer and the
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DevTools protocol. You can debug this by setting the < code > DEBUG< / code > environment
variable before running your script. This will log internal traffic via
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< a href = "https://github.com/visionmedia/debug" target = "_blank" rel = "noopener noreferrer" > < code > debug< / code > < / a > under the < code > puppeteer< / code > namespace.< / p >
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< div class = "language-bash codeBlockContainer_Ckt0 theme-code-block" style = "--prism-color:#393A34;--prism-background-color:#f6f8fa" > < div class = "codeBlockContent_biex" > < pre tabindex = "0" class = "prism-code language-bash codeBlock_bY9V thin-scrollbar" style = "color:#393A34;background-color:#f6f8fa" > < code class = "codeBlockLines_e6Vv" > < span class = "token-line" style = "color:#393A34" > < span class = "token comment" style = "color:#999988;font-style:italic" > # Basic verbose logging< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token function" style = "color:#d73a49" > env< / span > < span class = "token plain" > < / span > < span class = "token assign-left variable" style = "color:#36acaa" > DEBUG< / span > < span class = "token operator" style = "color:#393A34" > =< / span > < span class = "token string" style = "color:#e3116c" > " puppeteer:*" < / span > < span class = "token plain" > < / span > < span class = "token function" style = "color:#d73a49" > node< / span > < span class = "token plain" > script.js< / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token comment" style = "color:#999988;font-style:italic" > # Prevent truncating of long messages< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token function" style = "color:#d73a49" > env< / span > < span class = "token plain" > < / span > < span class = "token assign-left variable" style = "color:#36acaa" > DEBUG< / span > < span class = "token operator" style = "color:#393A34" > =< / span > < span class = "token string" style = "color:#e3116c" > " puppeteer:*" < / span > < span class = "token plain" > < / span > < span class = "token function" style = "color:#d73a49" > env< / span > < span class = "token plain" > < / span > < span class = "token assign-left variable" style = "color:#36acaa" > DEBUG_MAX_STRING_LENGTH< / span > < span class = "token operator" style = "color:#393A34" > =< / span > < span class = "token plain" > null < / span > < span class = "token function" style = "color:#d73a49" > node< / span > < span class = "token plain" > script.js< / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" style = "display:inline-block" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token comment" style = "color:#999988;font-style:italic" > # Protocol traffic can be rather noisy. This example filters out all Network domain messages< / span > < span class = "token plain" > < / span > < br > < / span > < span class = "token-line" style = "color:#393A34" > < span class = "token plain" > < / span > < span class = "token function" style = "color:#d73a49" > env< / span > < span class = "token plain" > < / span > < span class = "token assign-left variable" style = "color:#36acaa" > DEBUG< / span > < span class = "token operator" style = "color:#393A34" > =< / span > < span class = "token string" style = "color:#e3116c" > " puppeteer:*" < / span > < span class = "token plain" > < / span > < span class = "token function" style = "color:#d73a49" > env< / span > < span class = "token plain" > < / span > < span class = "token assign-left variable" style = "color:#36acaa" > DEBUG_COLORS< / span > < span class = "token operator" style = "color:#393A34" > =< / span > < span class = "token plain" > true < / span > < span class = "token function" style = "color:#d73a49" > node< / span > < span class = "token plain" > script.js < / span > < span class = "token operator file-descriptor important" style = "color:#393A34" > 2< / span > < span class = "token operator" style = "color:#393A34" > > < / span > < span class = "token file-descriptor important" > & 1< / span > < span class = "token plain" > < / span > < span class = "token operator" style = "color:#393A34" > |< / span > < span class = "token plain" > < / span > < span class = "token function" style = "color:#d73a49" > grep< / span > < span class = "token plain" > < / span > < span class = "token parameter variable" style = "color:#36acaa" > -v< / span > < span class = "token plain" > < / span > < span class = "token string" style = "color:#e3116c" > ' " Network' < / span > < span class = "token plain" > < / span > <
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< / body >
< / html >
