JavaScript 中是否有最佳实践或通用方法将类成员作为事件处理程序？
考虑以下简单示例：
<head>
<script language="javascript" type="text/javascript">
ClickCounter = function(buttonId) {
this._clickCount = 0;
document.getElementById(buttonId).onclick = this.buttonClicked;
}
ClickCounter.prototype = {
buttonClicked: function() {
this._clickCount++;
alert('the button was clicked ' + this._clickCount + ' times');
}
}
</script>
</head>
<body>
<input type="button" id="btn1" value="Click me" />
<script language="javascript" type="text/javascript">
var btn1counter = new ClickCounter('btn1');
</script>
</body>
事件处理程序 buttonClicked 被调用，但 _clickCount 成员不可访问，或者this指向其他一些对象。
关于此类问题有什么好的技巧/文章/资源吗？
ClickCounter = function(buttonId) {
this._clickCount = 0;
var that = this;
document.getElementById(buttonId).onclick = function(){ that.buttonClicked() };
}
ClickCounter.prototype = {
buttonClicked: function() {
this._clickCount++;
alert('the button was clicked ' + this._clickCount + ' times');
}
}
编辑近 10 年后，使用 ES6、箭头函数和类属性 https://babeljs.io/docs/plugins/transform-class-properties/
class ClickCounter {
count = 0;
constructor( buttonId ){
document.getElementById(buttonId)
.addEventListener( "click", this.buttonClicked );
}
buttonClicked = e => {
this.count += 1;
console.log(`clicked ${this.count} times`);
}
}
https://codepen.io/anon/pen/zaYvqq https://codepen.io/anon/pen/zaYvqq
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