分享一个js对象开发组件写法

var TextCount = (function(){
//私有方法，外面将访问不到
var _bind = function(that){
that.input.on('keyup',function(){
that.render();
});
}

var _getNum = function(that){
return that.input.val().length;
}

var TextCountFun = function(config){

}

TextCountFun.prototype.init = function(config) {
this.input = $(config.id);
_bind(this);

return this;
};

TextCountFun.prototype.render = function() {
var num = _getNum(this);

if ($('#J_input_count').length == 0) {
this.input.after('<span id="J_input_count"></span>');
};

$('#J_input_count').html(num+'个字');
};
//返回构造函数
return TextCountFun;

})();

$(function() {
new TextCount().init({id:'#J_input'}).render();
})

来自：http://blog.csdn.net/bingqingsuimeng/article/details/44451481