最近用到js筛选一个url的域名部分（草创）

var TLD = ['com','net','org','gov','edu','mil','biz','name','info','mobi','cn','hk'];
		var host = '';
		function start(){
		 	var regx = /(\w+\.){1,}\w+/;
		 	var inpt = document.getElementById('inpt');
		 	var txt = inpt.value.toLowerCase();
		 	var findTLD = function(arr){
		 		for(var j = 0;j<arr.length;j++){
		 			if(TLD.indexOf(arr[j])!=-1){
		 				return arr[j];
		 			}
		 		}
		 	};
		 	if(regx.test(inpt.value)){
		 		var matches = regx.exec(inpt.value)[0];
		 		var txtArr = matches.split('.');
		 		host = txtArr[txtArr.indexOf(findTLD(txtArr))-1];
		 		if(host){
		 			inpt.value = matches.slice(matches.indexOf(host));
		 		}else {
		 			alert('请输入正确的的URL');
		 		}
		 	}else{
		 		alert('请输入正确的的URL');
		 	}

		}