class: Frame

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2023-12-01

在每一个时间点，页面通过 page.mainFrame() 和 frame.childFrames() 方法暴露当前框架的细节。

Frame 对象的生命周期由 3 个事件控制，它们通过 page 对象监听：

'frameattached' - 当框架被页面加载时触发。一个框架只会被加载一次。
'framenavigated' - 当框架改变URL时触发。
'framedetached' - 当框架被页面分离时触发。一个框架只会被分离一次。

一个获得框架树的例子：

const puppeteer = require('puppeteer');

puppeteer.launch().then(async browser => {
  const page = await browser.newPage();
  await page.goto('https://www.google.com/chrome/browser/canary.html');
  dumpFrameTree(page.mainFrame(), '');
  await browser.close();

  function dumpFrameTree(frame, indent) {
    console.log(indent + frame.url());
    for (let child of frame.childFrames())
      dumpFrameTree(child, indent + '  ');
  }
});

一个从 iframe 元素中获取文本的例子：

  const frame = page.frames().find(frame => frame.name() === 'myframe');
  const text = await frame.$eval('.selector', element => element.textContent);
  console.log(text);

frame.$(selector)

selector <string> Selector to query frame for
returns: <Promise<?ElementHandle>> Promise which resolves to ElementHandle pointing to the frame element.

这个方法在框架中查询指定的选择器。如果在框架中没有匹配的元素会返回 null

frame.$$(selector)

selector <string> Selector to query frame for
returns: <Promise<Array<ElementHandle>>> Promise which resolves to ElementHandles pointing to the frame elements.

这个方法会在框架中执行 document.querySelectorAll 方法。如果没有元素匹配会返回 []

frame.$$eval(selector, pageFunction[, ...args])

selector <string> A selector to query frame for
pageFunction <function> Function to be evaluated in browser context
...args <...Serializable|JSHandle> Arguments to pass to pageFunction
returns: <Promise<Serializable>> Promise which resolves to the return value of pageFunction

这个方法会在框架中执行 Array.from(document.querySelectorAll(selector)) 方法，然后将返回值传给 pageFunction 函数的第一个参数。

如果 pageFunction 返回了一个Promise,那么 frame.$$eval 将会等待Promise resolve之后返回它的值。

例子：

const divsCounts = await frame.$$eval('div', divs => divs.length);

frame.$eval(selector, pageFunction[, ...args])

selector <string> A selector to query frame for
pageFunction <function> Function to be evaluated in browser context
...args <...Serializable|JSHandle> Arguments to pass to pageFunction
returns: <Promise<Serializable>> Promise which resolves to the return value of pageFunction

这个方法会在框架中执行 document.querySelector 方法，然后将返回值传给 pageFunction 函数的第一个参数。如果没有匹配到任何元素，则会抛出一个错误。

如果 pageFunction 返回了一个 Promise,那么 frame.$eval 将会等待 Promise 并解析后返回它的值。

例如:

const searchValue = await frame.$eval('#search', el => el.value);
const preloadHref = await frame.$eval('link[rel=preload]', el => el.href);
const html = await frame.$eval('.main-container', e => e.outerHTML);

frame.$x(expression)

expression <string> Expression to evaluate.
returns: <Promise<Array<ElementHandle>>>

这个方法用来执行 XPath 表达式。

frame.addScriptTag(options)

options <Object>
- url <string> URL of a script to be added.
- path <string> Path to the JavaScript file to be injected into frame. If path is a relative path, then it is resolved relative to current working directory.
- content <string> Raw JavaScript content to be injected into frame.
- type <string> Script type. Use 'module' in order to load a Javascript ES6 module. See script for more details.
returns: <Promise<ElementHandle>> which resolves to the added tag when the script's onload fires or when the script content was injected into frame.

将 url 或脚本内容添加到 <script> 标签中。

frame.addStyleTag(options)

options <Object>
- url <string> URL of the <link> tag.
- path <string> Path to the CSS file to be injected into frame. If path is a relative path, then it is resolved relative to current working directory.
- content <string> Raw CSS content to be injected into frame.
returns: <Promise<ElementHandle>> which resolves to the added tag when the stylesheet's onload fires or when the CSS content was injected into frame.

根据样式路径或内容往页面中添加 <link rel="stylesheet"> 或 <style type="text/css"> 样式标签。

frame.childFrames()

returns: <Array<Frame>>

frame.click(selector[, options])

selector <string> A selector to search for element to click. If there are multiple elements satisfying the selector, the first will be clicked.
options <Object>
- button <string> left, right, or middle, defaults to left.
- clickCount <number> defaults to 1. See UIEvent.detail.
- delay <number> Time to wait between mousedown and mouseup in milliseconds. Defaults to 0.
returns: <Promise> Promise which resolves when the element matching selector is successfully clicked. The Promise will be rejected if there is no element matching selector.

这个方法选择传入的元素，如果必要的话会将元素滚动到可视区域，之后使用 page.mouse 点击元素的内容。如果没有匹配到元素，会抛出异常。

注意：如果 click() 触发了导航事件，那么就会有一个由 page.waitForNavigation() 产生的 promise 要被解析，你可能会得到一个 promise 的竞争状态。正确的处理 click 和 wait for navigation 的方式如下：

const [response] = await Promise.all([
  page.waitForNavigation(waitOptions),
  frame.click(selector, clickOptions),
]);

frame.content()

returns: <Promise<String>>

获取框架完整的HTML内容，包括 doctype。

frame.evaluate(pageFunction, ...args)

pageFunction <function|string> Function to be evaluated in browser context
...args <...Serializable|JSHandle> Arguments to pass to pageFunction
returns: <Promise<Serializable>> Promise which resolves to the return value of pageFunction

如果传给 frame.evaluate 的函数返回了一个 promise，那么 frame.evaluate 将会等到 promise resolve 时返回它的值。

如果传给 frame.evaluate 的函数返回了一个非序列化的值，那么 frame.evaluate 将返回 undefined

const result = await frame.evaluate(() => {
  return Promise.resolve(8 * 7);
});
console.log(result); // 输出 "56"

也可以给函数传递字符串。

console.log(await frame.evaluate('1 + 2')); // 输出 "3"

ElementHandle 实例也可以作为 frame.evaluate 的参数：

const bodyHandle = await frame.$('body');
const html = await frame.evaluate(body => body.innerHTML, bodyHandle);
await bodyHandle.dispose();

frame.evaluateHandle(pageFunction, ...args)

pageFunction <function|string> Function to be evaluated in the page context
...args <...Serializable|JSHandle> Arguments to pass to pageFunction
returns: <Promise<JSHandle>> Promise which resolves to the return value of pageFunction as in-page object (JSHandle)

frame.evaluate 和 frame.evaluateHandle 唯一的不同是 frame.evaluateHandle 返回页面对象（JSHandle）。

如果传给 frame.evaluateHandle的函数返回了一个 Promise，那么 frame.evaluateHandle 将会等到 promise resolve 时返回它的值。

const aWindowHandle = await frame.evaluateHandle(() => Promise.resolve(window));
aWindowHandle; // Handle for the window object.

也可以向函数传递字符串。

const aHandle = await frame.evaluateHandle('document'); // Handle for the 'document'.

JSHandle 实例也可以作为 frame.evaluateHandle 的参数:

const aHandle = await frame.evaluateHandle(() => document.body);
const resultHandle = await frame.evaluateHandle(body => body.innerHTML, aHandle);
console.log(await resultHandle.jsonValue());
await resultHandle.dispose();

frame.executionContext()

returns: <Promise<ExecutionContext>>

返回解析为框架的默认执行上下文的 promise。

frame.focus(selector)

selector <string> 一个选择器元素。A selector of an element to focus. If there are multiple elements satisfying the selector, the first will be focused.
returns: <Promise> Promise which resolves when the element matching selector is successfully focused. The promise will be rejected if there is no element matching selector.

这个方法选择传入的元素并且使之获得焦点。如果没有匹配到元素，会抛出异常。

frame.goto(url, options)

url <string> URL to navigate frame to. The url should include scheme, e.g. https://.
options <Object> Navigation parameters which might have the following properties:
- timeout <number> Maximum navigation time in milliseconds, defaults to 30 seconds, pass 0 to disable timeout. The default value can be changed by using the page.setDefaultNavigationTimeout(timeout) method.
- waitUntil <string|Array<string>> When to consider navigation succeeded, defaults to load. Given an array of event strings, navigation is considered to be successful after all events have been fired. Events can be either:
  - load - consider navigation to be finished when the load event is fired.
  - domcontentloaded - consider navigation to be finished when the DOMContentLoaded event is fired.
  - networkidle0 - consider navigation to be finished when there are no more than 0 network connections for at least 500 ms.
  - networkidle2 - consider navigation to be finished when there are no more than 2 network connections for at least 500 ms.
- referer <string> Referer header value. If provided it will take preference over the referer header value set by page.setExtraHTTPHeaders().
returns: <Promise<?Response>> Promise which resolves to the main resource response. In case of multiple redirects, the navigation will resolve with the response of the last redirect.

如果存在下面的情况 frame.goto 将会抛出错误：

SSL 错误 (e.g. in case of self-signed certificates).
目标 URL 不可用。
导航过程中 timeout 被触发。
主资源加载失败。

注意 frame.goto抛出或返回一个主资源响应。唯一的例外是导航到about：blank或导航到具有不同 hash 的相同URL，这将成功并返回null。

注意无头模式将不支持导航到一个 PDF 文档。具体见 upstream issue.

frame.hover(selector)

selector <string> A selector to search for element to hover. If there are multiple elements satisfying the selector, the first will be hovered.
returns: <Promise> Promise which resolves when the element matching selector is successfully hovered. Promise gets rejected if there's no element matching selector.

这个方法选择传入的元素，如果必要的话会滚动到视野区域中，然后使用 page.mouse 方法将鼠标悬浮在元素的中心。

如果没有匹配到元素，会抛出异常。

frame.isDetached()

returns: <boolean>

如果框架不被加载了返回 true，否则返回 false。

frame.name()

returns: <string>

返回框架在标签中指定的 name 属性。

如果 name 为空，返回 id。

注意这个值在框架创建的时侯就就计算好了，如果之后修改属性的话不会更新。

frame.parentFrame()

returns: <?Frame> Returns parent frame, if any. Detached frames and main frames return null.

frame.select(selector, ...values)

selector <string> A selector to query frame for
...values <...string> Values of options to select. If the <select> has the multiple attribute, all values are considered, otherwise only the first one is taken into account.
returns: <Promise<Array<string>>> Returns an array of option values that have been successfully selected.

下拉框一旦选择了所提供的选项，change 和 input 事件将会被触发。

如果没有匹配到下拉框，会抛出异常。

frame.select('select#colors', 'blue'); // 单选
frame.select('select#colors', 'red', 'green', 'blue'); // 多选

frame.setContent(html)

html <string> HTML markup to assign to the page.
returns: <Promise>

frame.tap(selector)

selector <string> A selector to search for element to tap. If there are multiple elements satisfying the selector, the first will be tapped.
returns: <Promise>

这个方法选择传入的元素，如果必要的话会滚动到视野区域中，然后使用 page.touchscreen 方法单击元素中心。

如果没有匹配到元素，会抛出异常。

frame.title()

returns: <Promise<string>> Returns page's title.

frame.type(selector, text[, options])

selector <string> A selector of an element to type into. If there are multiple elements satisfying the selector, the first will be used.
text <string> A text to type into a focused element.
options <Object>
- delay <number> Time to wait between key presses in milliseconds. Defaults to 0.
returns: <Promise>

对于每一个文本中的字符执行 keydown、keypress / input, 和 keyup 事件

如果要输入特殊按键，比如 Control 或者 ArrowDown,使用 keyboard.press。

frame.type('#mytextarea', 'Hello'); // 立即输入
frame.type('#mytextarea', 'World', {delay: 100}); // 延迟输入, 操作更像用户

frame.url()

returns: <string>

返回框架的 url。

frame.waitFor(selectorOrFunctionOrTimeout[, options[, ...args]])

selectorOrFunctionOrTimeout <string|number|function> A selector, predicate or timeout to wait for
options <Object> Optional waiting parameters
...args <...Serializable|JSHandle> Arguments to pass to pageFunction
returns: <Promise<JSHandle>> Promise which resolves to a JSHandle of the success value

这个方法根据第一个参数类型的不同起到不同的作用：

如果 selectorOrFunctionOrTimeout 是 string，那么第一个参数会被当作 selector 或者 xpath，取决于是不是以//开头的，这是 frame.waitForSelector 或 frame.waitForXPath 的快捷方式。
如果 selectorOrFunctionOrTimeout 是 function，那么第一个参数会当作条件等待触发，这是 frame.waitForFunction() 的快捷方式。
如果 selectorOrFunctionOrTimeout 是 number，那么第一个参数会被当作毫秒为单位的时间，方法会在超时之后返回 promise。
其他类型，将会抛出错误。

// wait for selector
await page.waitFor('.foo');
// wait for 1 second
await page.waitFor(1000);
// wait for predicate
await page.waitFor(() => !!document.querySelector('.foo'));

将 node.js 中的参数传递给 page.waitFor 函数：

const selector = '.foo';
await page.waitFor(selector => !!document.querySelector(selector), {}, selector);

frame.waitForFunction(pageFunction[, options[, ...args]])

pageFunction <function|string> Function to be evaluated in browser context
options <Object> Optional waiting parameters
- polling <string|number> An interval at which the pageFunction is executed, defaults to raf. If polling is a number, then it is treated as an interval in milliseconds at which the function would be executed. If polling is a string, then it can be one of the following values:
  - raf - to constantly execute pageFunction in requestAnimationFrame callback. This is the tightest polling mode which is suitable to observe styling changes.
  - mutation - to execute pageFunction on every DOM mutation.
- timeout <number> maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout.
...args <...Serializable|JSHandle> Arguments to pass to pageFunction
returns: <Promise<JSHandle>> Promise which resolves when the pageFunction returns a truthy value. It resolves to a JSHandle of the truthy value.

waitForFunction 可以用来观察可视区域大小是否改变。

const puppeteer = require('puppeteer');

puppeteer.launch().then(async browser => {
  const page = await browser.newPage();
  const watchDog = page.mainFrame().waitForFunction('window.innerWidth < 100');
  page.setViewport({width: 50, height: 50});
  await watchDog;
  await browser.close();
});

将 node.js 中的参数传递给 page.waitForFunction 函数：

const selector = '.foo';
await page.waitForFunction(selector => !!document.querySelector(selector), {}, selector);

frame.waitForNavigation(options)

options <Object> Navigation parameters which might have the following properties:
- timeout <number> Maximum navigation time in milliseconds, defaults to 30 seconds, pass 0 to disable timeout. The default value can be changed by using the page.setDefaultNavigationTimeout(timeout) method.
- waitUntil <string|Array<string>> When to consider navigation succeeded, defaults to load. Given an array of event strings, navigation is considered to be successful after all events have been fired. Events can be either:
  - load - consider navigation to be finished when the load event is fired.
  - domcontentloaded - consider navigation to be finished when the DOMContentLoaded event is fired.
  - networkidle0 - consider navigation to be finished when there are no more than 0 network connections for at least 500 ms.
  - networkidle2 - consider navigation to be finished when there are no more than 2 network connections for at least 500 ms.
returns: <Promise<[?Response]>> Promise which resolves to the main resource response. In case of multiple redirects, the navigation will resolve with the response of the last redirect. In case of navigation to a different anchor or navigation due to History API usage, the navigation will resolve with null.

当框架导航到新 URL 时将被解析。它在运行代码时很有用。这将间接导致框架进行导航。看下这个例子：

const [response] = await Promise.all([
  frame.waitForNavigation(), // The navigation promise resolves after navigation has finished
  frame.click('a.my-link'), // Clicking the link will indirectly cause a navigation
]);

注意使用 History API 去改变 URL 将会被认为是导航。

frame.waitForSelector(selector[, options])

selector <string> A selector of an element to wait for
options <Object> Optional waiting parameters
- visible <boolean> wait for element to be present in DOM and to be visible, i.e. to not have display: none or visibility: hidden CSS properties. Defaults to false.
- hidden <boolean> wait for element to not be found in the DOM or to be hidden, i.e. have display: none or visibility: hidden CSS properties. Defaults to false.
- timeout <number> maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout.
returns: <Promise<ElementHandle>> Promise which resolves when element specified by selector string is added to DOM.

等待被选择等待元素出现在页面中。如果调用时选择的元素已存在，则立即返回。如果在设定的毫秒时间之后还没有出现，则抛出异常。

这个方法可以在切换导航时使用:

const puppeteer = require('puppeteer');

puppeteer.launch().then(async browser => {
  const page = await browser.newPage();
  let currentURL;
  page.mainFrame()
    .waitForSelector('img')
    .then(() => console.log('First URL with image: ' + currentURL));
  for (currentURL of ['https://example.com', 'https://google.com', 'https://bbc.com'])
    await page.goto(currentURL);
  await browser.close();
});

frame.waitForXPath(xpath[, options])

xpath <string> A xpath of an element to wait for
options <Object> Optional waiting parameters
- visible <boolean> wait for element to be present in DOM and to be visible, i.e. to not have display: none or visibility: hidden CSS properties. Defaults to false.
- hidden <boolean> wait for element to not be found in the DOM or to be hidden, i.e. have display: none or visibility: hidden CSS properties. Defaults to false.
- timeout <number> maximum time to wait for in milliseconds. Defaults to 30000 (30 seconds). Pass 0 to disable timeout.
returns: <Promise<ElementHandle>> Promise which resolves when element specified by xpath string is added to DOM.

等待 xpath 出现在页面中。如果在调用函数的时候 xpath 已经存在，会立即返回。如果在设定的毫秒时间之后还没有出现，则抛出异常。

这个方法可以在切换导航时使用:

const puppeteer = require('puppeteer');

puppeteer.launch().then(async browser => {
  const page = await browser.newPage();
  let currentURL;
  page.mainFrame()
    .waitForXPath('//img')
    .then(() => console.log('First URL with image: ' + currentURL));
  for (currentURL of ['https://example.com', 'https://google.com', 'https://bbc.com'])
    await page.goto(currentURL);
  await browser.close();
});