JavaScript 原型“这个”问题
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JavaScript prototype 'this' issue
提问by FlyingCat
This is a follow up question from my last question.
这是我上一个问题的后续问题。
Simple javascript prototype issue
I am a bit new using JavaScript prototypeso sorry for the second post.
我对 JavaScript 有点陌生，prototype所以很抱歉第二篇文章。
I want to assign the clicked element idto the this.namearray.
我想点击的元素分配id给this.name数组。
task.prototype.init=function(){
this.name=[]; //this.name array has to be defined here
for (var i; i<5; i++){
var Link=document.createElement('a');
Link.innerHTML='click';
Link.id=value[i]; //I want to assign the value to the this.name array
Link.href='#'
Link.onclick=this.changeName;
document.body.appendChild(Link);
}
}
task.prototype.changeName=function(){
//How do I push the this.id to the property this.name?
//the code below won't work because this refer to the <a> element.
this.name.push(this.id);
return false;
}
Any tips for the task?
任务有什么提示吗？
回答by bfavaretto
Your prototype is okay, the problem is that thison event handlers is always the element that caused the event to be triggered. In JavaScript, the value of thisinside a function depends on how the function is called.
你的原型没问题，问题是this事件处理程序总是导致事件被触发的元素。在 JavaScript 中，this函数内部的值取决于函数的调用方式。
If you want thisto be bound to a certain value, you can create a bound function with Function.prototype.bind:
如果要this绑定到某个值，可以使用以下命令创建绑定函数Function.prototype.bind：
var newChangeName = this.changeName.bind(this);
Link.onclick = newChangeName;
Note however that bindis IE9+ only. A workaround would be:
但请注意，这bind仅适用于 IE9+。一种解决方法是：
var that = this;
Link.onclick = function() {
that.changeName();
};
(Style note: I'd use linkinstead of Link; the convention in js is to leave uppercase initials to constructors).
（样式说明：我会使用link而不是Link; js 中的约定是将大写首字母留给构造函数）。
