<script>

    function suolve( str,sub_length ){

		var temp1 = str.replace(/[^\x00-\xff]/g,"**");//精髓

		var temp2 = temp1.substring(0,sub_length);

		//找出有多少个*

		var x_length = temp2.split("\*").length - 1 ;

		var hanzi_num = x_length /2 ;

		sub_length = sub_length - hanzi_num ;//实际需要sub的长度是总长度-汉字长度

		var res = str.substring(0,sub_length);

		if(sub_length < str.length ){

		   var end =res+"……" ;

		}else{

		   var end = res ;

		}

		   return end ;

	}

    var str1="1111哇咔咔咔";

    var str2="11哇11哇咔咔咔"

    console.log(suolve(str1,6));

    console.log(suolve(str2,6));

</script>