jquery实时搜索限制ajax发送频率

gistfile1.txt

 function getSearchText(){
        var btn = true
        $('.searchContent').off('input').on('input',function(){
            if(timer){
                clearTimeout(timer)
            } 
            if(!btn){
                return;
            }
            btn = false;
            var that =this;
            var timer=setTimeout(function(){
                btn = true
                var keyword = $(that).val();
                if(keyword == ''){
                    return;   
                }
                var param = 'keyword='+keyword;
                xhr.get(SITE_URL + 'supplychain/model/keyword', param, function(res){
                    console.log(res);
                });
            },500);
        });
    }