js中的this是怎么用的

以此为例

var net = {}

net.AjaxRequest = function (url, onload, onerror, method, params) {
    this.req = null;
    this.onload = onload;
    this.onerror = (onerror)  ? onerror : this.defaultError;
    this.loadDate(url, method,  params);
}

net.AjaxRequest.prototype.loadDate = function (url, method, params) {
    if (!method) {
       method = "GET";
    }
    if (window.XMLHttpRequest) {
        this.req = new XMLHttpRequest();
    }else if (window.ActiveXObject) {
        this.req = new ActiveXObject("Microsoft.XMLHTTP");
    }
    if (this.req) {
        try {
            var loader = this;
            this.req.onreadystatechange =  function () {
                net.AjaxRequest.onReadyState.call(loader);
            }
            this.req.open(method, url, true);
            if (method === "POST") {
                this.req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
                this.req.send(params);
            }
        }catch (err) {
            this.onerror.call(this);
        }
    }
}

net.AjaxRequest.onReadyState = function () {
    var req = this.req;
    var ready =  req.readyState;
    if (ready === 4)  {
        if (req.status === 200) {
            this.onload.call(this);
        }else {
            this.onerror.call(this);
        }
    }
}

net.AjaxRequest.prototype.defaultError = function () {
    alert("错误数据\n\n回调状态:" + this.req.readyState + "\n状态:" + this.req.status);
}

要详细的解释,每个this代表什么
不光这一个例子,都给我讲明白了,我不仅会采纳,还会给红包,直接打款到微信 15-30不等

• 你可以参考下这个问题的回答, 看看是否对你有帮助, 链接: https://ask.csdn.net/questions/7665065
• 这篇博客你也可以参考下：js 中的this指针
• 您还可以看一下 周振宇老师的JS完全解析第一章 - JS简介课程中的 JS在浏览器端的功能小节, 巩固相关知识点
  

说来话长，请看这里 https://blog.csdn.net/txun123/article/details/124236620