JSONJSONandand

A Comparison of ScriptsA Comparison of Scripts

JSON: JavaScript Object Notation

• Based on a subset of the JavaScript Programming Language

• provides a standardized data exchange format that is better-suited for Ajax-style web applications.

formal languages specifically designed to support the communication of data and metadata.

JSON: JavaScript Object Notation

• Language independant, but similar to C-family (C, Java, Perl, Python)

• Data formatted according to the JSON standard is lightweight and can be parsed by JavaScript implementations with incredible ease

JSON: JavaScript Object Notation

• Built on two structures:• Name/value pair• Ordered list of values

JSON literals

JSON: the difference

• JSON: much stricter rules. • name of an object member must be a valid JSON

string. • string must be enclosed in quotation marks.• array and object elements are limited to a set.

• No date/time literal (not in JavaScript either)

• No comments

Using JSON

• Use a script tag<script src="http://www.mysite.com/mydata.js"></script>

• Dynamically load a script tagfunction dhtmlLoadScript(url)

{

var e = document.createElement("script");

e.src = url;

e.type="text/javascript";

document.getElementsByTagName("head")[0].appendChild(e);

}

dhtmlLoadScript("http://www.mysite.com/mydata.js");

Using JSON

• Use AJAX to pull some text from the server and then eval it.

ajaxCaller.getPlainText("mydata.js", function(jsText)

{ eval(jsText); });

Server vs Client Side Scripting

Client-side Scripting

• Easy way to provide additional functionality and flexibility

• Downloaded, interpreted and executed by the browser

• Dependant on the client's capabilities (memory, CPU speed, video card)

• Lightweight, less full-featured language

• Examples: JavaScript, JScript, VBScript

Server-side Scripting

• Also enhances functionality, but usually less visible

• Used for content management (database)

• Runs on the server and depends on memory and CPU speed of the server

• Must be supported by the server

• Examples: PHP, ASP, Perl