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JSON Cheat Sheet by

A JSON cheat sheet.
arrays     data     json     types

Data Types

number
var myNum = 123.456;
Series of numbers; decimals ok; double­-pr­ecision floati­ng-­point format
string
var myString = "­abc­def­";
Series of characters (letters, numbers, or symbols); double­-quoted UTF-8 with backslash escaping
boolean
var myBool = true;
true or false
array
var myArray = [ "­a", "­b", "­c", "­d" ];
sequence of comma-­sep­arated values (any data type); enclosed in square brackets
object
var myObject = { "­id": 7 };
unordered collection of comma-­sep­arated key/value pairs; enclosed in curly braces; properties (keys) are distinct strings
null
var myNull = null;
variable with null (empty) value
undefined
var myUnde­fined;
variable with no value assigne
 

Objects

var myObject = {
  "first": "John",
  "last": "Doe",
  "age": 39,
  "sex": "male",
  "salary": 70000,
  "registered": true
};

Access object properties

myObje­ct.sex
returns "­mal­e"
myObje­ct[­"­age­"]
returns 39
myObje­ct[0]
returns "­Joh­n"
myObje­ct.s­om­ething
returns undefined
myObje­ct[6]
returns undefined

Array of objects

var myArray = [
  {
    "first": "John",
    "last": "Doe",
    "age": 39,
    "sex": "male",
    "salary": 70000,
    "registered": true
  },
  {
    "first": "Jane",
    "last": "Smith",
    "age": 42,
    "sex": "female",
    "salary": 80000,
    "registered": true
  },
  {
    "first": "Amy",
    "last": "Burnquist",
    "age": 29,
    "sex": "female",
    "salary": 60000,
    "registered": false
  }
];

Access array elements

myArray[0]
returns { "­fis­t": "­Joh­n", "­las­t": "­Doe­" ... }
myArray[1]
returns { "­fis­t": "­Jan­e", "­las­t": "­Smi­th" ... }
myArra­y[1­].first
returns "­Jan­e"
myArra­y[1][2]
returns 42
myArra­y[2­].r­egi­stered
returns false
myArray[3]
returns undefined
myArra­y[3­].sex
error: "­cannot read proper­ty..."
 

Arrays

var myArray = [
  "John",
  "Doe",
  39,
  "M",
  70000,
  true
];

Access array elements

myArray[1]
returns "­Doe­"
myArray[5]
returns true
myArray[6]
returns undefined

Nested objects and arrays

var myObject = {
  "ref": {
    "first": 0,
    "last": 1,
    "age": 2,
    "sex": 3,
    "salary": 4,
    "registered": 5
  },
  "jdoe1": [
    "John",
    "Doe",
    39,
    "male",
    70000,
    true
  ],
  "jsmith1": [
    "Jane",
    "Smith",
    42,
    "female",
    80000,
    true
  ]
};

Access nested elements

myObje­ct.r­ef.first
returns 0
myObje­ct.j­doe1
returns [ "­Joh­n", "­Doe­", 39 ... ]
myObje­ct[2]
returns [ "­Jan­e", "­Smi­th", 42 ... ]
myObje­ct.j­sm­ith1[3]
returns "­fem­ale­"
myObje­ct[­1][5]
returns true
myObje­ct.j­do­e1[­myO­bje­ct.r­ef.last]
returns "­Doe­"
myObje­ct.j­sm­ith­1[m­yOb­jec­t.r­ef.age]
returns 42

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Comments

DaveChild DaveChild, 09:46 9 Mar 15

Great reference, very handy!

Stephen Stephen, 15:57 23 Mar 15

You carried over some typos from https://www.json.com/cheat-sheet-v-1-3

You might correct "fist" to "first" in a few places.

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