The Ultimate JSON Cheat Sheet – Boost Your Productivity As An IT Professional

In this guide, we'll take a look at Hide

1) Data Types

2) Objects

3) Access object properties

4) Array of objects

5) Access array elements

6) Arrays

7) Access array elements

8) Nested objects and arrays

9) Access nested elements

JSON (JavaScript Object Notation) is a lightweight data interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. JSON is a text format that is completely language-independent but uses conventions that are familiar to programmers of the C family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language. Let’s start JSON Cheat Sheet.

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": <span class="hljs-literal">true</span>
};

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": <span class="hljs-literal">true</span>
  },
  {
    "first": "Jane",
    "last": "Smith",
    "age": 42,
    "sex": "female",
    "salary": 80000,
    "registered": <span class="hljs-literal">true</span>
  },
  {
    "first": "Amy",
    "last": "Burnquist",
    "age": 29,
    "sex": "female",
    "salary": 60000,
    "registered": <span class="hljs-literal">false</span>
  }
];

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 { “first”: “John”, “last”: “Doe” … }
myArray[1]	returns { “first”: “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,
  <span class="hljs-literal">true</span>
];

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,
    <span class="hljs-literal">true</span>
  ],
  "jsmith1": [
    "Jane",
    "Smith",
    42,
    "female",
    80000,
    <span class="hljs-literal">true</span>
  ]
};

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