手机号脱敏

//方法1
 var num = '12345678901'
    let phonenumber = num.replace(num.substring(3, 7), '****')
//方法2
function noPassByMobile(str) {
      if (null != str && str != undefined) {
          var pat = /(\d{3})\d*(\d{4})/;
          return str.replace(pat, '$1****$2');
      } else {
          return "";
      }
  }