[JS]截取字符,中英文都可以

//截取字符，中英文都可以，hasDot=true 返回值的最后还可以添加3个点

function subString(str, len, hasDot) {

    var newLength = 0;

    var newStr = "";

    var chineseRegex = /[^\x00-\xff]/g;

    var singleChar = "";

    var strLength = str.replace(chineseRegex, "**").length;

    for (var i = 0; i < strLength; i++) {

        singleChar = str.charAt(i).toString();

        if (singleChar.match(chineseRegex) != null) {

            newLength += 2;

        }

        else {

            newLength++;

        }

        if (newLength > len) {

            break;

        }

        newStr += singleChar;

    }

    if (hasDot && strLength > len) {

        newStr += "...";

    }

    return newStr;

}