无法从 JSON 字符串中删除键值对？

Question

On doing console.log(data.toString()) , I get the following output:

{
      "cid":"9333227",
      "status" : 30,
      "user" : "user1"
}

On doing console.log(data['cid']) before performing delete, I get undefined as the output

I want to remove the cid key value pair such that the console.log(data.toString()) should generate the following output:

{
      "status" : 30,
      "user" : "user1"
}

I am doing delete data['cid'] and then doing console.log(data.toString()) . However, it is still printing the original json

{
      "cid":"9333227",
      "status" : 30,
      "user" : "user1"
}

Answer 1

If you run data.toString()) , and get the output you got, means that data is not an object. It's likely a string.

If you run:

"hello".toString();

you get "hello".

If you run:

delete "hello".foo

You are deleting a non-existant property on the string, which works without error. It doesn't change the contents of the string.

So I think you don't have an object, you have a JSON string. To mutate it, you need to first parse it:

const obj = JSON.parse(data);
delete obj.cid;
console.log(obj);

If you need to turn it back into a JSON string, you can use JSON.stringify() .

Answer 2

let jsonobj = {
  "cid": "933227",
  "status": 30,
  "user": "user1",
}

delete jsonobj['cid']

console.log(JSON.stringify(jsonobj));

Try JSON.stringify() instead of .toString()