Json object and array and simple implementation method for converting to js object, jsonjs

Json object and array and simple implementation method for converting to js object, jsonjs

JSON syntax rules

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

• Data in name/value pairs
• Data is separated by commas (,).
• Brackets save objects
• Square brackets Save the Array

JSON object

JSON objects are written in curly brackets:

The object can contain multiple name/value pairs:

{ "firstName":"John" , "lastName":"Doe" } 

This is easy to understand and is equivalent to this JavaScript statement:

firstName = "John"lastName = "Doe"

JSON Array

JSON array is written in square brackets:

An array can contain multiple objects:

{ "employees": [ { "firstName":"John" , "lastName":"Doe" }, { "firstName":"Anna" , "lastName":"Smith" }, { "firstName":"Peter" , "lastName":"Jones" } ] } 

In the preceding example, the object "employees" is an array containing three objects. Each object represents a record about someone (with a surname and a name.

JSON File

• The JSON file type is ". json"
• The MIME type of JSON text is "application/json"

Convert JSON text to JavaScript Object

The JavaScript function eval () can be used to convert JSON text to JavaScript objects.

The eval () function uses a JavaScript compiler that parses JSON text and generates JavaScript objects. Text must be enclosed in parentheses to avoid syntax errors:
Var obj = eval ("(" + jsontxt + ")");

Example:

$. Ajax ({type: 'post', url: '.../caseHandler. ashx? Action = GetCase & id = '+ id. toString (), // url action is the method name data: "", dataType: "text", // It Can Be text. If text is used, the returned result is a string; if json format is required, you can set it to json ContentType: "application/json; charset = UTF-8", success: function (returnedData) {getMarkerFeature (eval ("(" + returnedData + ")") ;}, error: function (msg) {alert ("Access failed: "+ msg );}});

Create an object array using JavaScript

var employees = [{ "firstName":"Bill" , "lastName":"Gates" },{ "firstName":"George" , "lastName":"Bush" },{ "firstName":"Thomas" , "lastName": "Carter" }];

Two methods for accessing JavaScript Object Attributes

Object. attribute

Object ["attribute"]

For example:

Var employees = [{"firstName": "Bill", "lastName": "Gates" },{ "firstName": "George", "lastName": "Bush "}, {"firstName": "Thomas", "lastName": "Carter"}]; alert (employees [0]. lastName); // method 1 alert (employees [0] ["lastName"]); // method 2

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