- JSON (json.org)
- JSON Editor Online (jsoneditoronline.org)
- Convert JSON Array to Markdown Table, CSV and more (tableconvert.com)
JSON Cheat Sheet
This is a quick reference cheat sheet for understanding and writing JSON format configuration files.
Also see
Access JSON in JavaScript
Access Array
let myArray = [
"Jason",
"Doe",
39,
"M",
70000,
true
];
myArray[1] |
"Doe" |
myArray[5] |
true |
myArray[6] |
undefined |
Access Array of Objects
let myArray = [
{
"name": "Jason",
"last": "Doe",
"age": 39,
"gender": "M",
"salary": 70000,
"married": true
},
{
"name": "Tom",
"last": "Smith",
"age": 42,
"gender": "F",
"salary": 80000,
"married": true
},
{
"name": "Amy",
"last": "Burnquist",
"age": 29,
"gender": "F",
"salary": 60000,
"married": false
}
];
myArray[0] |
{ "name": "Jason", …} |
myArray[1].name |
"Tom" |
myArray[1][2] |
42 |
myArray[3] |
undefined |
myArray[3].gender |
TypeError: Cannot read… |
Access Nested
let myObject = {
"ref": {
"name": 0,
"last": 1,
"age": 2,
"gender": 3,
"salary": 4,
"married": 5
},
"jdoe": [
"Jason",
"Doe",
39,
"M",
70000,
true
],
"jsmith": [
"Tom",
"Smith",
42,
"F",
80000,
true
]
};
myObject.ref.age |
2 |
myObject["ref"]["age"] |
2 |
myObject.jdoe |
["Jason", "Doe", 39 …] |
myObject.jsmith[3] |
"F" |
myObject[1] |
undefined |
Access Object
let myObject = {
"name": "Jason",
"last": "Doe",
"age": 39,
"gender": "M",
"salary": 70000,
"married": true
};
myObject.name |
"Jason" |
myObject["name"] |
"Jason" |
myObject.age |
39 |
myObject.other |
undefined |
myObject[0] |
undefined |
Getting Started
Nested
{
"Jack": {
"id": 1,
"name": "Franc",
"salary": 25000,
"hobby": ["a", "b"],
"location": {
"country": "A", "city": "A-A"
}
}
}
Object of objects
{
"Mark McGwire": {
"hr": 65,
"avg": 0.278
},
"Sammy Sosa": {
"hr": 63,
"avg": 0.288
}
}
2D Array
{
"my\_sequences": [
[1, 2, 3],
[4, 5, 6],
[7, 8, 9, 0],
[10, 11]
]
}
Object of arrays
{
"attributes": ["a1", "a2"],
"methods": ["getter", "setter"],
"empty\_array": []
}
Array of objects
{
"children": [
{"name": "Jimmy Smith", "age": 15},
{"name": "Sammy Sosa", "age": 12}
]
}
Arrays
[1, 2, 3, 4, 5]
Begins with [
and ends with ]
Objects
{
"color": "Purple",
"id": "210",
"composition": {
"R": 70,
"G": 39,
"B": 89
},
"empty\_object": {}
}
Multiple key/value pairs separated by a comma
Number
Type | Description |
---|---|
Integer |
Digits 1-9, 0 and positive or negative |
Fraction |
Fractions like 0.3, 3.9 |
Exponent |
Exponent like e, e+, e-, E, E+, E |
#Examples
{
"positive" : 12,
"negative" : -1,
"fraction" : 10.25,
"exponent" : 1.0E+2,
"zero" : 0
}
#Invalid Number
{ "foo": 0xFF }
In JSON you can use only Decimal Literals
String
\" |
Double quote |
\\ |
Backslash |
\/ |
Forward slash |
\b |
Backspace |
\f |
Form feed |
\n |
Newline |
\r |
Carriage return |
\t |
Tab |
\u |
Trailed by four hex digits |
#Examples
{
"url": "https://quickref.me",
"msg" : "Hi,\n\"QuickRef.ME\"",
"intro": "Share quick reference and cheat sheet for developers."
}
#Invalid String
{ "foo": 'bar' }
Have to be delimited by double quotes
Types
Type | Description |
---|---|
Number |
Double precision floating-point |
String |
Series of characters |
Boolean |
true or false |
Array |
Ordered sequence of values |
Value |
String, Number, Boolean, null etc |
Object |
Unordered collection of key/value pairs |
null |
Null or Empty |
Examples
{
"name": "Jason",
"age": 39,
"height": 1.92,
"gender": "M",
"salary": 70000,
"married": true,
"children": [
{"name": "Tom", "age": 9, "gender":"M"},
{"name": "Ava", "age": 7, "gender":"F"}
]
}
Introduction
JSON is a lightweight text-based open standard designed for human-readable data interchange.
- JSON stands for JavaScript Object Notation
- JSON is easy to read and write.
- JSON is language agnostic data-interchange format
- JSON filename extension is
.json
- JSON Internet Media type is
application/json