Is json a subset of javascript?

JSON syntax is a subset of JavaScript syntax. JSON is a lightweight data exchange format. It is based on a subset of ECMAScript and uses a text format that is completely independent of programming languages ​​to store and represent data.

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

JSON syntax is a subset of JavaScript syntax.

1. JSON syntax rules:

JSON syntax is a subset of JavaScript object notation syntax.

(1) Data is in name/value pairs

(2) Data is separated by commas

(3) Curly braces save objects

(4) Square brackets save the array

2. JSON name-value pair

The writing format of JSON data is: name/value pair.

A name/value pair consists of the field name (in double quotes), followed by a colon, and then the value:

"name" : "liming" Equivalent to name="liming"

3. JSON value

• Number (integer or floating point number)

• String (in double quotes)

• Logical value (true or false)

• Array (in square brackets)

• Object (In curly brackets)

• null

4. JSON object

JSON object is written in curly brackets:

The object can contain multiple name/value pairs:

{ "name" : "a" , "age" : 34}

5. JSON array

JSON arrays are written in square brackets:

Arrays can contain multiple objects:

{
“employees” :[
{"name"  : "a"  ,  "sex"  :  "nv"}，
{"name"  : "b"  ,  "sex"  :  "nan"}，
{"name"  : "c"  ,  "sex"  :  "nv"}
]
}

In the above example, the object "employees" is an array containing three objects . Each object represents a record about a person.

6. JSON uses JavaScript syntax

Example

var  employees = [
{"name"  : "a"  ,  "sex"  :  "nv"}
{"name"  : "b"  ,  "sex"  :  "nan"}
{"name"  : "c"  ,  "sex"  :  "nv"}
];

You can access the first item in the JavaScript object array like this:

employees[0]. name;

The returned content is: a

Modify data:

employee[0].name= "zhangsan";

Since JSON syntax is a subset of JavaScript syntax, the JavaScript function eval() can be used to convert JSON text is a JavaScript object.

Because the eval() function uses a JavaScript compiler, it can parse JSON text and then generate JavaScript objects. Text must be enclosed in brackets to avoid syntax errors:

For example:

var obj = eval ("(" txt ")");

[Recommended learning: javascript advanced tutorial]

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