精确控制SQL排序顺序(Fine control over SQL Sort Order)

 PhantomJS的page.open()是一个异步函数。 最早在完全传输和解析对页面请求的响应时调用其回调。 在调用回调时没有明确定义，但根据经验我会说，一旦所有直接资源也被加载（不是异步资源），它总会被调用。 
 
 这意味着在页面上触发DOMContentLoaded事件后很长时间调用回调。 这反过来意味着如果你在激活后注册到DOMContentLoaded，你的事件处理程序将永远不会触发。 
 
 现在它看起来像这样： 
 
page.evaluate(function(){
    var links = document.querySelectorAll('a.link');
    Array.prototype.forEach.call(links, function(e){ 
        e.click();
    });
});
 
 问题是element.click()在大多数页面上都不起作用。 PhantomJS的问题; 点击一个元素有多种解决方案来应对这种困境。 你这样做： 
 
page.evaluate(function(){
    var links = document.querySelectorAll('a.link');
    Array.prototype.forEach.call(links, function(e){
        var ev = document.createEvent('MouseEvents');
        ev.initMouseEvent('click', true, true, window, 0, 0, 0, 0, 0, 
                false, false, false, false, 0, null);
        e.dispatchEvent(ev);
    });
});

PhantomJS's page.open() is an asynchronous function. Its callback is called at the earliest when the response to the page request was fully transmitted and parsed. It's not clearly defined when exactly the callback is called, but from experience I would say it is always called as soon as all immediate resources are also loaded (not async resources).
 
This means that the callback is called long after the DOMContentLoaded event was triggered on the page. Which in turn means that if you register to the DOMContentLoaded after it was fired, your event handler will never fire.
 
Now it looks like this:
 
page.evaluate(function(){
    var links = document.querySelectorAll('a.link');
    Array.prototype.forEach.call(links, function(e){ 
        e.click();
    });
});
 
The problem is that element.click() doesn't work on most pages. The question PhantomJS; click an element has multiple solutions for this predicament. You do it like this:
 
page.evaluate(function(){
    var links = document.querySelectorAll('a.link');
    Array.prototype.forEach.call(links, function(e){
        var ev = document.createEvent('MouseEvents');
        ev.initMouseEvent('click', true, true, window, 0, 0, 0, 0, 0, 
                false, false, false, false, 0, null);
        e.dispatchEvent(ev);
    });
});