In JavaScript, structured data is often represented using JSON (JavaScript Object Notation), which is a lightweight, text-based format for organizing and storing data. JSON is widely used for data interchange in web applications due to its simplicity and compatibility with JavaScript objects.
JSON Structure Basics
A JSON structure is composed of:
1. Key-value pairs: Each key is a string, and values can be strings, numbers, objects, arrays, true
, false
, or null
.
2. Arrays: Ordered lists of values.
3. Nested objects and arrays: JSON supports nesting, allowing you to build complex data structures.
JSON Example
Here’s an example of structured data in JSON format:
{
"name": "Alice",
"age": 30,
"isStudent": false,
"courses": ["Math", "Physics", "Chemistry"],
"address": {
"street": "123 Main St",
"city": "New York",
"zipCode": "10001"
},
"scores": [
{ "course": "Math", "score": 95 },
{ "course": "Physics", "score": 88 },
{ "course": "Chemistry", "score": 92 }
]
}
JSON in JavaScript
In JavaScript, JSON is often used as a format for data received from or sent to a server in an API request/response. JSON is easily converted to and from JavaScript objects.
1. Converting JSON to JavaScript Object
- You can parse JSON data (in string format) into a JavaScript object using
JSON.parse()
.
const jsonString = '{"name": "Alice", "age": 30}';
const user = JSON.parse(jsonString);
console.log(user.name); // Output: "Alice"
2. Converting JavaScript Object to JSON
- You can convert a JavaScript object to a JSON string using
JSON.stringify()
.
const user = { name: "Alice", age: 30 };
const jsonString = JSON.stringify(user);
console.log(jsonString); // Output: '{"name":"Alice","age":30}'
Nested JSON Structure
JSON supports nesting, allowing for complex data representations:
{
"product": "Laptop",
"details": {
"brand": "BrandName",
"specs": {
"cpu": "Intel i7",
"ram": "16GB",
"storage": "512GB SSD"
}
},
"reviews": [
{ "user": "User1", "rating": 5, "comment": "Excellent!" },
{ "user": "User2", "rating": 4, "comment": "Good value" }
]
}
Common Uses of JSON in JavaScript
1. API Data Exchange: JSON is often used to send and receive data between client and server in APIs.
2. Configuration Files: JSON is used to config files in various applications and frameworks.
3. Data Storage: JSON can be stored in local storage or databases for use in JavaScript applications.
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