Frame.waitForFunction() 方法
¥Frame.waitForFunction() method
签名
¥Signature
class Frame {
waitForFunction<
Params extends unknown[],
Func extends EvaluateFunc<Params> = EvaluateFunc<Params>,
>(
pageFunction: Func | string,
options?: FrameWaitForFunctionOptions,
...args: Params
): Promise<HandleFor<Awaited<ReturnType<Func>>>>;
}
参数
¥Parameters
范围 | 类型 | 描述 |
---|---|---|
pageFunction | 功能 | 字符串 | 在框架上下文中评估的函数。 |
options | (可选)用于配置轮询方法和超时的选项。 | |
args | 参数 | 要传递给 |
Returns:
Promise<HandleFor<Awaited<ReturnType<Func>>>>
当 pageFunction
返回真值时解决的 promise。
¥the promise which resolve when the pageFunction
returns a truthy value.
示例
¥Example
waitForFunction
可用于观察视口大小的变化:
¥The waitForFunction
can be used to observe viewport size change:
import puppeteer from 'puppeteer';
(async () => {
. const browser = await puppeteer.launch();
. const page = await browser.newPage();
. const watchDog = page.mainFrame().waitForFunction('window.innerWidth < 100');
. page.setViewport({width: 50, height: 50});
. await watchDog;
. await browser.close();
})();
要将参数从 Node.js 传递到 page.waitForFunction
函数的谓词:
¥To pass arguments from Node.js to the predicate of page.waitForFunction
function:
const selector = '.foo';
await frame.waitForFunction(
selector => !!document.querySelector(selector),
{}, // empty options object
selector
);