json_api.md

Fancy things you can do with JSON.stringify()

Replacer

var user = {
  name: 'andy',
  isAdult: false,
  age: 11,
  addr: 'sydney'
};

JSON.stringify(user, (k, v) => {
  if (k === 'isAudlt') {
    return v === true ? 1 : 0;
  }
  
  return v;
});

// {"name":"andy","isAdult":0,"age":11,"addr":"sydney"}

Delete a property

var user = {
  name: 'andy',
  isAdult: false,
  age: 11,
  addr: 'sydney'
};

var res = JSON.stringify(user, (k, v) => {
  if (k === 'isAdult') {
    return;
  }

  return v;
});

// {"name":"andy","age":11,"addr":"sydney"}

Remove unwanted properties

Use JSON.stringify

var user = {
  name: 'andy',
  isAdult: false,
  age: 11,
  addr: 'sydney'
};

var res = JSON.stringify(user, ['name', 'addr']);

// '{"name":"andy","addr":"sydney"}'

// or this to achieve the same result
JSON.stringify(foo, (key, value) => {
  if (key === '__typename') {
    return undefined;
  }
  return value;
});

Use JSON.parse

const res = JSON.parse('{"p": 5}', (key, value) =>
    key === 'p'
    ? undefined // return value * 2 for numbers
    : value     // return everything else unchanged
);

console.log(res); // {}

Format result

var user = {
  name: 'andy',
  isAdult: false,
  age: 11,
  addr: 'sydney'
};

var res = JSON.stringify(user, null, 2);

// {
//  "name": "andy",
//  "isAdult": false,
//  "age": 11,
//  "addr": "sydney"
// }

Deep clone

var user = {
  name: 'andy',
  isAdult: false,
  age: 11,
  addr: 'sydney'
};

JSON.parse(JSON.stringify(user)) // DO NOT DO IT ON LARGE JSON OBJECT - PERFORMANCE PROBLEM

Note, JSON.parse takes two arguments - 1st is the string to parse, 2nd is replacer same as JSON.stringify