JSON Basics

Shyamala Prayaga

Yodlee®, Inc. Copyright © 2009 - 04/10/2023 - CONFIDENTIAL 2

Agenda

• What is JSON?

• Why JSON?

• Pros and Cons

• JSON Syntax

• JSON Parser

• Accessing Data in JSON

Yodlee®, Inc. Copyright © 2009 - 04/10/2023 - CONFIDENTIAL 3

What is JSON?

• Stands for JavaScript Object Notation

• Is lightweight format for exchanging data between the client and server.

• Easy for humans to read and write.

• Easy for machines to parse and generate

• Often used in Ajax applications due to

– Its simplicity– its format which is based on JavaScript object literals

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Why JSON?

• JSON is recognized natively by JavaScript

• Simple format

• The easiness of reading

• The easiness of using

• Lighter than XML

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Benefits over XML

JSON XMLJSON object are type XML data is typeless

JSON types: string, number, array, boolean XML data are all string

Data is readily accessible as JSON objects XML data needs to be parsed

Retrieving value is easy Retrieving value is difficult

JSON is supported by all browsers Cross browser XML parsing can be tricky

Simple API Complex API

Supported by many Ajax toolkit Not fully supported by Ajax toolkit

Fast object de-serialization in JavaScript Slower de-serialization in JavaScript

Fully automated way of de-serializing/serializing JavaScript objects

Developers have to write JavaScript code to serialize/de-serialize to/from XML

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Pros and Cons

Pros Cons

Fast to parse No namespace support, hence poor extensibility

Good support for all browsers Limited development tools support

Supported by many languages No support for formal grammar definition

Concise format: name/value pair -based approach Easy to read

Easy to write

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JSON Syntax

• For objects start the object with “{“ and end it with “}”

• For members (properties), use pairs of string : value and separate them by commas

• For arrays put the arrays between []

• For elements put the values directly separated by commas

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Example

var myFirstJSON = {

"firstName" : "John",

      "lastName" : "Doe",

      "age"       : 23

};

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JSON Parser

• You can convert JSON object into JSON text

• Object to Text Conversion

var myJSONText = myObject.toJSONString();

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Accessing Data in JSON

• The most common way to access JSON data is through dot notation.

var myObject = { 'color' : 'blue' };

document.writeln(myObject.color);

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Questions?