javascript - Assign event listener from js class

Question

I want to assign onclick event listener to an object from within a class and then get some variable from the instance that created that onclick

function myclass() {

    this.myvar;

    this.myfunc = function() 
    {
        alert(this.myvar);
        document.onmousedown = this.mouseDown;        
    }

    this.mouseDown = function(e) 
    {
        alert(this.myvar); //does not work of course
        //how could I access myvar from current myclass instance
    }

}


var myclass_instance = new myclass();
    myclass_instance.myvar = 'value'
    myclass_instance.myfunc();

http://jsfiddle.net/E7wK4/

Answer 1

this在mouseDown事件不是this实例的情况下。

试试这个：

function myclass() {

    var _this = this;

    this.myvar;

    this.myfunc = function() 
    {
        alert(this.myvar);
        document.onmousedown = this.mouseDown;        
    }

    this.mouseDown = function(e) 
    {
        alert(_this.myvar); //<<<<
    }

}

演示：http: //jsfiddle.net/maniator/E7wK4/1/

Answer 2

作为@Neal 的替代方案，您可以绑定它。

document.onmousedown = this.mouseDown.bind(this);