js 练习

function En_test (options){ //初始化
    this.oImg = this.getId(options.id).getElementsByTagName("img");
    this.img_src = [],
    this.img_title = [],
    this.len = this.oImg.length;
    this.curr = 0;
    this.init.apply(this,arguments); 
};
En_test.prototype = {
    init : function(){
        var _that = this;
        this.getData();
        for( var i = 0; i < this.len; i++){
            this.oImg[i].index = i;
            this.oImg[i].onclick = function(){
                 _that.curr = this.index;
                console.log(_that.curr)
            }
        }
    },
    getId : function(id){
        return document.getElementById(id);
    },
    getData : function(){
        for (var i = 0; i < this.len ; i++ ){
            var src = this.oImg[i].getAttribute("data-src"),
                title = this.oImg[i].getAttribute("alt");
            this.img_src.push(src);
            this.img_title.push(title);
        }
        console.log(this.img_src);
    }
}