JSON Cheat Sheet

A Programming › JavaScript cheat sheet in English by Mackan90096

A JSON cheat sheet.

74,241 views 16,085 downloads 9 Mar 2015 History

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4.4 avg · 10 ratings

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 (5)

rroyster 20:29 2 Oct 2020

Great cheatsheet.

donaldpian 19:43 15 Jun 2020

Still having difficulty download loading PDF of JSON Cheatsheet.

donaldpian 19:42 15 Jun 2020

I having some difficulty downloading the JSON cheatsheet I probably need to Add a Comment.

Stephen 15:57 23 Mar 2015

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.

DaveChild 09:46 9 Mar 2015

Great reference, very handy!