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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
issues.</p><h2 class="anchor anchorWithStickyNavbar_LWe7" id="background">Background<a class="hash-link" href="#background" title="Direct link to heading"></a></h2><p>In general, there are two possible sources of an issue: Code running on Node.js
(which we call <em>server code</em>), and
<a href="/guides/[`Page.evaluate()`](../api/puppeteer.page.evaluate)">code running in the browser</a>
(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
<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 class="hash-link" href="#debugging-methods-for-all-situations" title="Direct link to heading"></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.headless"><code>headless</code></a><a class="hash-link" href="#turn-off-headless" title="Direct link to heading"></a></h3><p>Sometimes it&#x27;s useful to see what the browser is displaying. Instead of
launching in
<a href="/api/puppeteer.browserlaunchargumentoptions.headless"><code>headless</code></a>
mode, launch a full version of the browser with
<a href="/api/puppeteer.browserlaunchargumentoptions.headless"><code>headless</code></a>
set to <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"><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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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 &quot;slow-mo&quot;<a class="hash-link" href="#puppeteer-slow-mo" title="Direct link to heading"></a></h3><p>The <a href="/api/puppeteer.browserconnectoptions.slowmo"><code>slowMo</code></a>
option slows down Puppeteer operations by a specified amount of milliseconds.
It&#x27;s another way to help see what&#x27;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"><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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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 class="hash-link" href="#debugging-methods-for-client-code" title="Direct link to heading"></a></h2><h3 class="anchor anchorWithStickyNavbar_LWe7" id="capture-console-output">Capture <code>console.*</code> output<a class="hash-link" href="#capture-console-output" title="Direct link to heading"></a></h3><p>Since client code runs in the browser, doing <code>console.*</code> in client code will not
directly log to Node.js. However, you can
<a href="/api/puppeteer.page.on">listen</a> for the
<a href="/api/puppeteer.pageeventobject.console"><code>console</code></a> event which
returns a 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"><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">&#x27;console&#x27;</span><span class="token punctuation" style="color:#393A34">,</span><span class="token plain"> msg </span><span class="token operator" style="color:#393A34">=&gt;</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">&#x27;PAGE LOG:&#x27;</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">=&gt;</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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,1
<a href="/api/puppeteer.browserlaunchargumentoptions.devtools"><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"><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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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"><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">=&gt;</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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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>debug
debug mode.</p></li></ol><h2 class="anchor anchorWithStickyNavbar_LWe7" id="debugging-methods-for-server-code">Debugging methods for server code<a class="hash-link" href="#debugging-methods-for-server-code" title="Direct link to heading"></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 class="hash-link" href="#use-the-debugger-in-nodejs-chromechromium-only" title="Direct link to heading"></a></h3><p>Since server code intermingles with client code, this method of debugging is
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
browser.</p><p>Note that you won&#x27;t be able to run <code>await page.click()</code> in DevTools console due
to this
<a href="https://bugs.chromium.org/p/chromium/issues/detail?id=833928" target="_blank" rel="noopener noreferrer">Chromium bug</a>, so
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.headless"><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"><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">&#x27;a[target=_blank]&#x27;</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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">node --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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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="use-ndb">Use <a href="https://github.com/GoogleChromeLabs/ndb" target="_blank" rel="noopener noreferrer">ndb</a><a class="hash-link" href="#use-ndb" title="Direct link to heading"></a></h3><ol><li><p>Install <code>ndb</code>:</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">npm install -g ndb</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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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> 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"><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">&#x27;a[target=_blank]&#x27;</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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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>ndb</code> before your test command. For example,</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain">ndb node 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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path 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>Debug your test inside chromium like a boss!</p></li></ol><h3 class="anchor
DevTools protocol. You can debug this by setting the <code>DEBUG</code> environment
variable before running your script. This will log internal traffic via
<a href="https://github.com/visionmedia/debug" target="_blank" rel="noopener noreferrer"><code>debug</code></a> under the <code>puppeteer</code> namespace.</p><div class="language-sh codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-sh codeBlock_bY9V thin-scrollbar"><code class="codeBlockLines_e6Vv"><span class="token-line" style="color:#393A34"><span class="token plain"># Basic verbose logging</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">env DEBUG=&quot;puppeteer:*&quot; node 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"># Protocol traffic can be rather noisy. This example filters out all Network domain messages</span><br></span><span class="token-line" style="color:#393A34"><span class="token plain">env DEBUG=&quot;puppeteer:*&quot; env DEBUG_COLORS=true node script.js 2&gt;&amp;1 | grep -v &#x27;&quot;Network&#x27;</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 class="copyButtonIcon_y97N" viewBox="0 0 24 24"><path 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 class="copyButtonSuccessIcon_LjdS" viewBox="0 0 24 24"><path d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></span></button></div></div></div></div></article><nav class="pagination-nav docusaurus-mt-lg" aria-label="Docs pages navigation"><a class="pagination-nav__link pagination-nav__link--prev" href="/guides/configuring-puppeteer"><div class="pagination-nav__sublabel">Previous</div><div class="pagination-nav__label">Configuring Puppeteer</div></a><a class="pagination-nav__link pagination-nav__link--next" href="/guides/docker"><div class="pagination-nav__sublabel">Next</div><div class="pagination-nav__label">Docker</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#background" class="table-of-contents__link toc-highlight">Background</a></li><li><a href="#debugging-methods-for-all-situations" class="table-of-contents__link toc-highlight">Debugging methods for all situations</a><ul><li><a href="#turn-off-headless" class="table-of-contents__link toc-highlight">Turn off <code>headless</code></a></li><li><a href="#puppeteer-slow-mo" class="table-of-contents__link toc-highlight">Puppeteer &quot;slow-mo&quot;</a></li></ul></li><li><a href="#debugging-methods-for-client-code" class="table-of-contents__link toc-highlight">Debugging methods for client code</a><ul><li><a href="#capture-console-output" class="table-of-contents__link toc-highlight">Capture <code>console.*</code> output</a></li><li><a href="#use-the-debugger-in-the-browser" class="table-of-contents__link toc-highlight">Use the debugger in the browser</a></li></ul></li><li><a href="#debugging-methods-for-server-code" class="table-of-contents__link toc-highlight">Debugging methods for server code</a><ul><li><a href="#use-the-debugger-in-nodejs-chromechromium-only" class="table-of-contents__link toc-highlight">Use the debugger in Node.js (Chrome/Chromium-only)</a></li><li><a href="#use-ndb" class="table-of-contents__link toc-highlight">Use ndb</a></li><li><a href="#log-devtools-protocol-traffic" class="table-of-contents__link toc-highlight">Log DevTools protocol traffic</a></li></ul></li></ul></div></div></div></div></main></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Community</div><ul class="footer__items clean-li
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