最基本的API

var api = {
	//插件参数设定
	config: function (opts) {
		if(!opts) return options;
		for(var key in opts) {
			options[key] = opts[key];
		}
		return this;
	},
	//插件监听
	listen: function listen(elem) {
		if (typeof elem === ‘string‘) {
			var elems = document.querySelectorAll(elem),
				i = elems.length;
				while (i--) {
					listen(elems[i]);
				}
				return
		}
		//插件功能函数可以写在这
		return this;
	}
}
//将API赋值给插件名字
this.pluginName = api;