箭头函数的另一种写法
//function(){...}.bind(obj)
//方法返回的是方法本身，但是方法的this指向了obj
oReq.onload = function() {
var content = oReq.responseText;
callback( content );
}.bind( this );
模拟作业
browser.qq.com/mac/ blog.csdn.net/luyinchangd… www.htmleaf.com/Demo/201412… www.htmleaf.com/Demo/201810… www.htmleaf.com/Demo/201807…
