格式化输出:

let obj = {
    a: 'a1',b: 'b1'
};
JSON.stringify(obj,null,2);
//{
  "a": "a1","b": "b1"
}

巧用深拷贝:

let obj = {
    a: 'a1',b: 'b1'
};
let copy = JSON.stringify(obj);
let copyObj = JSON.parse(copy);
copyObj.c = 0;
//{a: "a1",b: "b1",c: 0}
//{a: "a1",b: "b1"}

再有发现会陆续添加进来