Improve documentation for the page.waitFor method.

Fixes #109.

docs/api.md

@@ -58,7 +58,7 @@
     + [page.uploadFile(selector, ...filePaths)](#pageuploadfileselector-filepaths)
     + [page.url()](#pageurl)
     + [page.viewport()](#pageviewport)
-    + [page.waitFor(target[, options])](#pagewaitfortarget-options)
+    + [page.waitFor(selectorOrTimeout[, options])](#pagewaitforselectorortimeout-options)
     + [page.waitForNavigation(options)](#pagewaitfornavigationoptions)
     + [page.waitForSelector(selector[, options])](#pagewaitforselectorselector-options)
   * [class: Keyboard](#class-keyboard)
@@ -87,7 +87,7 @@
     + [frame.name()](#framename)
     + [frame.parentFrame()](#frameparentframe)
     + [frame.url()](#frameurl)
-    + [frame.waitFor(target[, options])](#framewaitfortarget-options)
+    + [frame.waitFor(selectorOrTimeout[, options])](#framewaitforselectorortimeout-options)
     + [frame.waitForSelector(selector[, options])](#framewaitforselectorselector-options)
   * [class: Request](#class-request)
     + [request.headers](#requestheaders)
@@ -603,12 +603,17 @@ This is a shortcut for [page.mainFrame().url()](#frameurl)
 #### page.viewport()
 - returns: <[Object]>  An object with the save fields as described in [page.setViewport](#pagesetviewportviewport)
 
-#### page.waitFor(target[, options])
-- `target` <[string]|[number]> A target to wait for.
-- `options` <[Object]> Optional waiting parameters.
+#### page.waitFor(selectorOrTimeout[, options])
+- `selectorOrTimeout` <[string]|[number]> A selector or timeout to wait for
+- `options` <[Object]> Optional waiting parameters
 - returns: <[Promise]>
 
-Shortcut for [page.mainFrame().waitFor()](#framewaitfortargetoptions).
+This method behaves differently with respect to the type of the first parameter:
+- if `selectorOrTimeout` is a `string`, than the first argument is treated as a selector to wait for and the method is a shortcut for [frame.waitForSelector](#framewaitforselectorselectoroptions)
+- if `selectorOrTimeout` is a `number`, than the first argument is treated as a timeout in milliseconds and the method returns a promise which resolves after the timeout
+- otherwise, an exception is thrown
+
+The method is a shortcut for [page.mainFrame().waitFor()](#framewaitfortargetoptions).
 
 #### page.waitForNavigation(options)
 - `options` <[Object]> Navigation parameters, same as in [page.navigate](#pagenavigateurl-options).
@@ -837,14 +842,14 @@ Returns frame's name as specified in the tag.
 
 Returns frame's url.
 
-#### frame.waitFor(target[, options])
-- `target` <[string]|[number]> A target to wait for
+#### frame.waitFor(selectorOrTimeout[, options])
+- `selectorOrTimeout` <[string]|[number]> A selector or timeout to wait for
 - `options` <[Object]> Optional waiting parameters
 - returns: <[Promise]>
 
-This method behaves differently wrt the type of the first parameter:
-- if `target` is a `string`, than target is treated as a selector to wait for and the method is a shortcut for [frame.waitForSelector](#framewaitforselectorselectoroptions)
-- if `target` is a `number`, than target is treated as timeout in milliseconds and the method returns a promise which resolves after the timeout
+This method behaves differently with respect to the type of the first parameter:
+- if `selectorOrTimeout` is a `string`, than the first argument is treated as a selector to wait for and the method is a shortcut for [frame.waitForSelector](#framewaitforselectorselectoroptions)
+- if `selectorOrTimeout` is a `number`, than the first argument is treated as a timeout in milliseconds and the method returns a promise which resolves after the timeout
 - otherwise, an exception is thrown
 
 #### frame.waitForSelector(selector[, options])

lib/FrameManager.js

@@ -252,16 +252,16 @@ class Frame {
   }
 
   /**
-   * @param {(string|number)} target
+   * @param {(string|number)} selectorOrTimeout
    * @param {!Object=} options
    * @return {!Promise}
    */
-  waitFor(target, options = {}) {
-    if (typeof target === 'string' || target instanceof String)
-      return this.waitForSelector(target, options);
-    if (typeof target === 'number' || target instanceof Number)
-      return new Promise(fulfill => setTimeout(fulfill, target));
-    return Promise.reject(new Error('Unsupported target type: ' + (typeof target)));
+  waitFor(selectorOrTimeout, options = {}) {
+    if (typeof selectorOrTimeout === 'string' || selectorOrTimeout instanceof String)
+      return this.waitForSelector(selectorOrTimeout, options);
+    if (typeof selectorOrTimeout === 'number' || selectorOrTimeout instanceof Number)
+      return new Promise(fulfill => setTimeout(fulfill, selectorOrTimeout));
+    return Promise.reject(new Error('Unsupported target type: ' + (typeof selectorOrTimeout)));
   }
 
   /**

lib/Page.js

@@ -585,12 +585,12 @@ class Page extends EventEmitter {
   }
 
   /**
-   * @param {string} target
+   * @param {string} selectorOrTimeout
    * @param {!Object=} options
    * @return {!Promise<undefined>}
    */
-  waitFor(target, options) {
-    return this.mainFrame().waitFor(target, options);
+  waitFor(selectorOrTimeout, options) {
+    return this.mainFrame().waitFor(selectorOrTimeout, options);
   }
 
   /**