https://github.com/thedvlprs/json_parse
:tada: JavaScript JSON.parse Tutorial
https://github.com/thedvlprs/json_parse
arrays javascript json-parse reviver-function stringify values
Last synced: 11 months ago
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:tada: JavaScript JSON.parse Tutorial
- Host: GitHub
- URL: https://github.com/thedvlprs/json_parse
- Owner: thedvlprs
- Created: 2020-06-18T14:55:51.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2020-06-18T14:56:29.000Z (over 5 years ago)
- Last Synced: 2025-01-31T15:17:22.375Z (about 1 year ago)
- Topics: arrays, javascript, json-parse, reviver-function, stringify, values
- Language: JavaScript
- Homepage:
- Size: 787 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# JavaScript JSON.parse Tutorial
JavaScript JSON.parse tutorial shows how to parse JSON strings into JavaScript objects.
## JSON
**JSON (JavaScript Object Notation)** is a lightweight data-interchange format. It is easy for humans to read and write and for machines to parse and generate. The official Internet media type for JSON is `application/json`. The JSON filename extension is `.json`.
## JSON.parse
The `JSON.parse()` method parses a JSON string and creates a JavaScript value or object described by the string. An optional **reviver function** can be provided to perform a transformation on the resulting object before it is returned. The reverse operation is performed with `JSON.stringify()`.
## JSON.parse values
In the first example, we parse JSON strings into JavaScript values.
`parse_values.js`
```js
console.log(JSON.parse('-3'));
console.log(JSON.parse('12'));
console.log(JSON.parse('true'));
console.log(JSON.parse('"falcon"'));
```
The example parses and prints `integers`, a `boolean value` and a `string`.
`$ node parse_values.js`
`-3`
`12`
`true`
`falcon`
This is the output.
## JSON.parse array
The next example parses a JSON array string into a JavaScript array.
`parse_array.js`
```js
let data = `[
{
"id": 1,
"first_name": "Robert",
"last_name": "Schwartz",
"email": "rob23@gmail.com"
},
{
"id": 2,
"first_name": "Lucy",
"last_name": "Ballmer",
"email": "lucyb56@gmail.com"
},
{
"id": 3,
"first_name": "Anna",
"last_name": "Smith",
"email": "annasmith23@gmail.com"
}
]`;
let users = JSON.parse(data);
console.log(typeof users)
console.log(users[1])
console.log(users);
```
We have a JSON string consisting of users. The string is parsed into a JavaScript array.
`let users = JSON.parse(data);`
The data is parsed.
`console.log(typeof users)`
We determine the data type of the returned data.
`console.log(users[1])`
We print the second user.
`console.log(users);`
We print the whole array.
`$ node parse_list.js`
```json
object
{
id: 2,
first_name: 'Lucy',
last_name: 'Ballmer',
email: 'lucyb56@gmail.com'
}
[
{
id: 1,
first_name: 'Robert',
last_name: 'Schwartz',
email: 'rob23@gmail.com'
},
{
id: 2,
first_name: 'Lucy',
last_name: 'Ballmer',
email: 'lucyb56@gmail.com'
},
{
id: 3,
first_name: 'Anna',
last_name: 'Smith',
email: 'annasmith23@gmail.com'
}
]
```
This is the output.
## JSON.parse reviver function
The `JSON.parse()` function can take an optional reviver function as the second parameter. It can perform a transformation on the resulting object before it is returned.
`reviver.js`
```js
let data = '{ "name": "John Doe", "dateOfBirth": "1976-12-01", "occupation": "gardener"}';
let user = JSON.parse(data, (k, v) => {
if (k == "dateOfBirth") {
return new Date(v);
} else {
return v;
}
});
console.log(user);
```
In the example, we use the **reviver function** to transform a string property into a date.
## JSON.stringify
The `JSON.stringify()` function converts a JavaScript object or value to a JSON string.
`stringify.js`
```js
let users = [
{
id: 1,
first_name: 'Robert',
last_name: 'Schwartz',
email: 'rob23@gmail.com'
},
{
id: 2,
first_name: 'Lucy',
last_name: 'Ballmer',
email: 'lucyb56@gmail.com'
},
{
id: 3,
first_name: 'Anna',
last_name: 'Smith',
email: 'annasmith23@gmail.com'
}
];
let data = JSON.stringify(users);
console.log(typeof data);
console.log(typeof users);
console.log(data);
console.log(users);
```
In the example, we have an array of users. We transform the array into a JSON string with the `JSON.stringify()` function.
`$ node stringify.js`
```json
string
object
[{"id":1,"first_name":"Robert","last_name":"Schwartz","email":"rob23@gmail.com"},
{"id":2,"first_name":"Lucy","last_name":"Ballmer","email":"lucyb56@gmail.com"},
{"id":3,"first_name":"Anna","last_name":"Smith","email":"annasmith23@gmail.com"}]
[
{
id: 1,
first_name: 'Robert',
last_name: 'Schwartz',
email: 'rob23@gmail.com'
},
{
id: 2,
first_name: 'Lucy',
last_name: 'Ballmer',
email: 'lucyb56@gmail.com'
},
{
id: 3,
first_name: 'Anna',
last_name: 'Smith',
email: 'annasmith23@gmail.com'
}
]
```
This is the output.
In this tutorial, we have **parsed JSON strings into JavaScript objects with the** `JSON.parse()` **function**.