JSON and JavaScript objects

var obj={width:100,height:200}, which is not called JSON, and JSON is just a data format, not a concrete instance.

But many people think of such a JS object as JSON, the following to clarify the problem

First, JSON What is it? ( What is the difference between JSON and JavaScript objects?) How do i convert a JS object to a JSON string? And how to convert a JSON string into a JavaScript object?

JSON (JavaScript Object Notation) is a lightweight data interchange format , JSON-formatted data, primarily for cross-platform exchange of data.

But JSON and JavaScript do have roots, which can be said to evolve from JavaScript objects, which are a subset of JavaScript. The JSON itself means JavaScript Object Notation (Notation), which uses strict JavaScript Object notation to represent structured data.

It is a strict format of the JS object, the JSON property name must have double quotation marks, if the value is a string, also must be double quotation marks;

JSON is just a data format (or data form), the data format is actually a specification, format, form, specification can not be used to save data. We cannot call the following objects JSON, for example:

<script>

var obj2={};//this is just a JS object

var obj3={width:100,height:200};/* this is not the same as JSON, just JS Object */

var obj5={"width": +, "height": $, "name": "Rose"}; /* We can call this: a JSON-formatted JavaScript Object */

var str1= ' {' width ': $, ' height ': $, ' name ': ' Rose '} ';/* We can call this: a JSON-formatted string */

var a=[

{"width": +, "height": $, "name": "Rose"},

{"width": +, "height": $, "name": "Rose"},

{"width": +, "height": $, "name": "Rose"},

];

/* This is a JSON-formatted array, which is a slightly more complex form of JSON */

var str2= ' [' +

' {' width ': +, ' height ': $, ' name ': ' Rose '}, ' +

' {' width ': +, ' height ': $, ' name ': ' Rose '}, ' +

' {' width ': +, ' height ': $, ' name ': ' Rose '}, ' +

'] ' ;

/* This is called a slightly more complex JSON-formatted string */

</script>

JSON and JS object comparison table

Difference	Json	Javascript Object
Meaning	is just a data format	Represents an instance of a class
Transmission	Can transfer data across platforms with fast speed	Cannot transmit
Performance	1, key value pair mode, key must be double quotation mark 2, the value cannot be a method function, not a Undefined/nan	1, key value pair mode, key without quotation marks 2, values can be functions, objects, strings, numbers, Boolean, and so on
Convert each other	Convert JSON to JS object: 1, Json.parse (jsonstring); (not compatible with IE7) 2, Jsobj=eval ("(" +jsonstring+ ")"); (Compatible with all browsers, but not secure, will execute the JSON inside the expression?)	The JS object is converted to JSON: Json.stringify (jsobj);(incompatible IE7)
Other	Invoke the JSON website JS to implement the parse and stringify compatibility in each browser : Https://github.com/douglascrockford/JSON-js/blob/master/json2.js

JSON and JavaScript objects