JS Note--json

1. What's the JSON:

JSON refers to JavaScript Object notation (JavaScript object Notation),

JSON is a lightweight text data interchange format;

JSON is independent of language;

JSON is self-descriptive and easier to understand;

JSON uses JavaScript syntax to describe data objects, but JSON is still independent of languages and platforms, and JSON parsers and JSON libraries support many different programming languages.

2.json-convert to JavaScript object:

The JSON text format is syntactically identical to the code that creates the JavaScript object.

Therefore, without a parser, JavaScript programs can use the built-in eval () function to generate native JavaScript objects with JSON data.

3.json Syntax:

JSON syntax is a subset of the JavaScript Object notation syntax.

4.json format: Name/value pairs, name-value pairs include field names (in double quotes), followed by a colon, and then a value

JSON object: {"FirstName": "John", "LastName": "Doe"}

　　

JSON array: {"Employees": [{"Flrstname": "John", "LastName": "Doe", "FirstName": "Anna", "LastName": "Smith"}]}

　　　　

Convert 5.json text to JavaScript objects:

The JavaScript function eval () can be used to convert the JSON text to a JavaScript object.

var txt = ' {' Employees ': [        ' + ' {' firstName ': ' Bill ', ' lastName ': ' Gates '},        ' + ' {' firstName ': ' George ', ' lastName ":" Bush "},        ' + ' {" FirstName ":" Thomas "," LastName ":" Carter "}]} '
;
var obj=eval (' (' +txt+ ') ');

<script type= "Etxt/javascript" >
document.getElementById (' fname '). Innerhtml=obj.employees[1].firstname;
document.getElementById (' lname '). Innerhtml=obj.employees[1].lastname;
</script>

(Outside a JSON ' employees ', inside is an array, the inside of the array is JSON,)

6.json Read

1.var json={name: ' Miaov ', Age:23,fun: ' Web '}

for (Var sttr in JSON) {

alert (attr);

}

　　　　

2.var json={' name ': ' Miaov ', ' age ': $, ' fun ': ' Web '}

for (Var sttr in JSON) {

Alert (json[attr]);

}

JS Note--json