修改json对象的每一个值

function fun1(obj){
  var names={};
    /*for in 可以用于数组或者对象*/
  for(var name in obj){
    names[name] = obj[name].toLowerCase()
  }
  console.log(names);
};
var obj1 = {username: 'NAME', password: 'WOSHIDHS123'};
fun1(obj1);