Page.evaluateOnNewDocument() 方法

🌐 Page.evaluateOnNewDocument() method

添加将在以下场景之一调用的函数：

🌐 Adds a function which would be invoked in one of the following scenarios:

• 每当页面被导航时
• 每当子帧被附加或导航时。在这种情况下，该函数会在新附加的帧的上下文中被调用。

该函数在文档创建后但在其任何脚本运行之前被调用。这对于修改 JavaScript 环境很有用，例如，初始化 Math.random。

🌐 The function is invoked after the document was created but before any of its scripts were run. This is useful to amend the JavaScript environment, e.g. to seed Math.random.

语法

🌐 Signature

class Page {
  abstract evaluateOnNewDocument<
    Params extends unknown[],
    Func extends (...args: Params) => unknown = (...args: Params) => unknown,
  >(
    pageFunction: Func | string,
    ...args: Params
  ): Promise<NewDocumentScriptEvaluation>;
}

参数

🌐 Parameters

范围 🌐 Parameter	类型 🌐 Type	描述 🌐 Description
pageFunction	函数 | 字符串 🌐 Func | string	要在浏览器上下文中评估的函数 🌐 Function to be evaluated in browser context
args	参数 🌐 Params	传递给 pageFunction 的参数 🌐 Arguments to pass to pageFunction

返回:

Promise<NewDocumentScriptEvaluation>

示例

🌐 Example

在页面加载之前覆盖 navigator.languages 属性的示例：

🌐 An example of overriding the navigator.languages property before the page loads:

// preload.js

// overwrite the `languages` property to use a custom getter
Object.defineProperty(navigator, 'languages', {
  get: function () {
    return ['en-US', 'en', 'bn'];
  },
});

// In your puppeteer script, assuming the preload.js file is
// in same folder of our script.
const preloadFile = fs.readFileSync('./preload.js', 'utf8');
await page.evaluateOnNewDocument(preloadFile);