如何使PhantomJS等待页面上的特定条件 [英] How to make PhantomJS wait for a specific condition on the page

问题描述

我想实现这样的东西:

function(){
     var ua = page.evaluate(function() {
         while (document.getElementById("td_details87").parentElement.children[11].textContent == "Running" ) {
              console.log ("running.....");
              sleep(10000); //10 seconds
         }; 
         console.log ("DONE");
     });
},

我如何实现睡眠功能，是否有一个while循环?

How can I realize the sleep function and is there a while loop?

推荐答案

JavaScript中没有阻塞sleep()函数.如果您想睡觉，则必须使用某些异步功能，例如setTimeout(callback, timeout).

There is no blocking sleep() function in JavaScript. If you want to sleep then you have to use some asynchronous function like setTimeout(callback, timeout).

PhantomJS的examples文件夹中有一个函数可以执行您要尝试的操作.它是 waitFor(testFx, onReady[, timeout]) .通过一遍又一遍地调用测试函数直到返回真实值来进行工作.

There is a function in the examples folder of PhantomJS that does what you're trying to do. It's waitFor(testFx, onReady[, timeout]). It works by calling the test function over and over again until it returns a truthy value.

在您的情况下，看起来像这样:

In your case that would look like this:

waitFor(function _test(){
    return page.evaluate(function() {
        return document.getElementById("td_details87").parentElement.children[11].textContent == "Running"; 
    });
}, function _onReady(){
    console.log ("DONE");
});

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