js中报错不是一个函数

在下面的代码中：报错说hhFn()不是一个函数这是为啥呢
h5.prototype = {

    init:function(){
        this.bindEvent();
    },
    moveFn:function(diff){
        for(var i = 0;i<aLi.length;i++){
            aLi[i].className = "";
            adiv[i].className = "";
        }
        if(diff<0){
            aLi.eq(index+1).className = "selected";
            aDiv.eq(index+1).className = "selected";
            if(index == 3){
                index = -1;
            }
        }else{
            aLi.eq(index-1).className = "selected";
            aDiv.eq(index-1).className = "selected";
            if(index == 0){
                index == 4;
            }
        }
    },
    touchStartFn:function(event){
        var that = this,
            touch = event.touches[0];
        startX = touch.pageX;
    },
    hhFn:function(){
        console.log("zzz");
    },
    touchMoveFn:function(event){
            touch = event.touches[0],
            x = touch.pageX,
            index = this.getAttribute("index"),
            diff = x - startX;
        this.hhFn();**为啥在这里会说hhFn()不是一个函数**
    },
   
    bindEvent:function(){
            var that = this;
            for(var i = 0;i<aLi.length;i++){
                aDiv[i].addEventListener('touchstart', that.touchStartFn, false);
                aDiv[i].addEventListener('touchmove', that.touchMoveFn, false);
            }
    }
};
new h5;`请输入代码`

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你那个h5不是个构造函数。。。
首先你要

function h5(){
}
h5.prototype={
}

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闭包里面不要用this，var that = this;that.hhFn();