hover事件优化（延时操作）

$.fn.extend({
    delayed : function(fn1,fn2,time){
        time = time || 150
        var _this = this;
        
        _this.delayedTimer = null;
        return $(this).mouseenter(function(){
            clearTimeout(_this.delayedTimer);
            _this.delayedTimer = setTimeout(function (){
                fn1.call(_this);                
            },time)
        }).mouseleave(function(){
            clearTimeout(_this.delayedTimer);
            _this.delayedTimer = setTimeout(function (){
                fn2.call(_this);                
            },time)
        })
    }
})