XMLHttpRequest 中的 onload 是否等于 readyState==4? [英] Is onload equal to readyState==4 in XMLHttpRequest?

问题描述

我对 xhr 返回事件感到困惑，据我所知，onreadystatechange --> readyState == 4 和 onload 之间没有太大区别，是真的吗?

I am confuse about the xhr return event, as I can tell, there are not so much different between onreadystatechange --> readyState == 4 and onload, is it true?

var xhr = new XMLHttpRequest();
xhr.open("Get", url, false);
xhr.onreadystatechange = function() {
    if (xhr.readyState === 4)
    {
        /* do some thing*/
    }
};

xhr.send(null);

或

xhr.onload = function() { /* do something */ }

推荐答案

应该是一样的.onload 是在 XMLHttpRequest 2 中添加的，而 onreadystatechange 从原始规范开始就已经存在了.

It should be the same thing. onload was added in XMLHttpRequest 2 whereas onreadystatechange has been around since the original spec.

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