var character = ‘sd13564349471中‘;//字符

//1.判断该字符串里是否包含数字
function getNum(text){

var value = text.replace(/[^0-9]/ig,"");
return value;
}

//2.if包含数字，判断数据长度是否为11
if(getNum(character).length == 11){

//3.截取所有数字，并用*替换4，4
var phNum = getNum(character),
phnumAfter = phNum.substr(0,3) + "****" + phNum.substr(7);
}

//4.替换输出
var result = character.replace(phNum,phnumAfter);
console.log(result)//结果 为sd135****9471中

手机号中间四位用*号代替