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title: JSON date: 2021-09-14 18:26:55 background: bg-[#646464] tags: - config - format categories: - Programming intro: | This is a quick reference cheat sheet for understanding and writing JSON format configuration files. plugins: - copyCode

Getting Started

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

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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" }
	]
}

Types

String {.row-span-3}

Examples

{
	"url": "https://cheatsheets.zip",
	"msg": "Hi,\n\"CheatSheets.zip\"",
	"intro": "Share quick reference and cheat sheet for developers."
}

Invalid String

{ "foo": "bar" }

Have to be delimited by double quotes

Number {.row-span-2}

Examples

{
	"positive": 12,
	"negative": -1,
	"fraction": 10.25,
	"exponent": 1.0e2,
	"zero": 0
}

Invalid Number

{ "foo": 0xff }

In JSON you can use only Decimal Literals

Objects

{
	"color": "Purple",
	"id": "210",
	"composition": {
		"R": 70,
		"G": 39,
		"B": 89
	},
	"empty_object": {}
}

Multiple key/value pairs separated by a comma

Arrays

[1, 2, 3, 4, 5]

Begins with [ and ends with ]

Array of objects

{
	"children": [
		{ "name": "Jimmy Smith", "age": 15 },
		{ "name": "Sammy Sosa", "age": 12 }
	]
}

Object of arrays

{
	"attributes": ["a1", "a2"],
	"methods": ["getter", "setter"],
	"empty_array": []
}

2D Array

{
	"my_sequences": [
		[1, 2, 3],
		[4, 5, 6],
		[7, 8, 9, 0],
		[10, 11]
	]
}

Object of objects

{
	"Mark McGwire": {
		"hr": 65,
		"avg": 0.278
	},
	"Sammy Sosa": {
		"hr": 63,
		"avg": 0.288
	}
}

Nested

{
	"Jack": {
		"id": 1,
		"name": "Franc",
		"salary": 25000,
		"hobby": ["a", "b"],
		"location": {
			"country": "A",
			"city": "A-A"
		}
	}
}

Access JSON in JavaScript

Access Object

let myObject = {
	name: 'Jason',
	last: 'Doe',
	age: 39,
	gender: 'M',
	salary: 70000,
	married: true
};

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Access Nested {.row-span-2}

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]
};

---

Access Array of Objects {.row-span-2}

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
	}
];

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Access Array

let myArray = ['Jason', 'Doe', 39, 'M', 70000, true];

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Also see {.cols-1}

• JSON (json.org)
• JSON Editor Online (jsoneditoronline.org)
• Convert JSON Array to Markdown Table, CSV and more (tableconvert.com)