up：等待N秒钟，然后继续下一行 [英] puppeteer: wait N seconds before continuing to the next line

问题描述

在 puppeteer 中，我想等待一段确定的时间，然后再转到下一行代码。

In puppeteer I would like to wait a defined time before going to the next line of code.

我尝试放置一个 setTimeout 在评估函数中，但似乎只是被忽略

I've tried to put a setTimeout in an evaluate function but it seems to be simply ignored

console.log('before waiting');
await page.evaluate(async() => {
  setTimeout(function(){
      console.log('waiting');
  }, 4000)
});
console.log('after waiting');

此代码无需等待，只需在等待之前写 和在等待之后 / em>

This code don't wait and just write before waiting and after waiting

您知道怎么做吗？

推荐答案

您可以使用一个小的承诺函数，

You can use a little promise function,

function delay(time) {
   return new Promise(function(resolve) { 
       setTimeout(resolve, time)
   });
}

然后，在需要延迟的时候调用它。

Then, call it whenever you want a delay.

console.log('before waiting');
await delay(4000);
console.log('after waiting');

如果必须使用puppeteer，请使用内置的waitFor函数。

If you must use puppeteer use the builtin waitFor function.

await page.waitFor(4000)

如果仍然要使用page.evaluate，请在4​​秒钟后解决。您没有解决任何问题。

If you still want to use page.evaluate, resolve it after 4 seconds. You are not resolving anything.

await page.evaluate(async() => {
    await new Promise(function(resolve) { 
           setTimeout(resolve, 1000)
    });
});

但是我想您可以简单地使用前两个示例。

But I guess you can simply use the first two examples.

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