如何通过引用 javascript 中的事件处理程序来传递变量？
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How to pass a variable by reference to an event handler in javascript?
提问by frogatto
I simulated a class in java script, It's code is here:
我在java脚本中模拟了一个类，它的代码在这里：
function myclass()
{
this.count ;
this.init = function(){
$("div.mybtn").click({n:this},function(e){
e.data.n.count++;
});
}
this.getCount = function(){
alert(this.count);
}
}
Then I created an instance of this class and executed it's method init(),But when I click on any div.mybtnelement, It did not increment the value of this.count.
It seems the object thiswas passed to event handler by value not by reference.
How I can pass a variable to an event handler by reference?
Thanks for any help
然后我创建了这个类的一个实例并执行了它的方法init()，但是当我点击任何div.mybtn元素时，它并没有增加this.count.
似乎该对象this是通过值而不是引用传递给事件处理程序的。
如何通过引用将变量传递给事件处理程序？
谢谢你的帮助
采纳答案by Barmar
Javascript doesn't have pass-by-reference parameters. For what you want, you should use a closure variable:
Javascript 没有传递引用参数。对于你想要的，你应该使用一个闭包变量：
this.init = function(){
var self = this;
$("div.mybtn").click(function(){
self.count++;
});
}
回答by adeneo
You can't increment undefined, you have to start somewhere:
你不能 increment undefined，你必须从某个地方开始：
function myclass() {
this.count=0; // start counting at zero !!!
this.init = function(){
$("div.mybtn").on('click', {n:this},function(e){
e.data.n.count++;
e.data.n.getCount();
});
}
this.getCount = function(){
console.log(this.count);
}
}
var c = new myclass();
c.init()
回答by mohkhan
You can write a bind function and bind the context with the event handler.
您可以编写一个绑定函数并将上下文与事件处理程序绑定。
Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments), object = args.shift();
return function(){
fn.apply(object, args.concat(Array.prototype.slice.call(arguments)));
}
}
function myclass()
{
this.count ;
this.clicked = function(){
this.count++;
};
this.init = function(){
$("div.mybtn").click(this.clicked.bind(this));
}
this.getCount = function(){
alert(this.count);
}
}
