覆盖“this"变量问题或如何调用成员函数?

I have this class where I am using a combination of jQuery and Prototype:

var MyClass = Class.create({
    initElements: function(sumEl) {
       this.sumEl = sumEl;
       sumEl.keyup(this.updateSumHandler);
    },

    updateSumHandler: function(event) {
       // Throws error here: "this.updateSum is not a function"
       this.updateSum();
    },

    updateSum: function() {
       // does something here
    }
});

我到底如何调用 this.updateSum()?

推荐答案

你需要使用闭包.

 initElements: function(sumEl) {
        this.sumEl = sumEl;
        var ref = this;
        sumEl.keyup( function(){ref.updateSumHandler();});
 },