Uniform Resource Identifier

In information technology, a Uniform Resource Identifier (URI) is a string of characters used to identify a resource. Such identification enables interaction with representations of the resource over a network, typically the World Wide Web, using specific protocols. Schemes specifying a concrete syntax and associated protocols define each URI. The most common form of URI is the Uniform Resource Locator (URL), frequently referred to informally as a web address. More rarely seen in usage is the Uniform Resource Name (URN), which was designed to complement URLs by providing a mechanism for the identification of resources in particular namespaces.

Relationships among URIs, URLs, and URNs

A Uniform Resource Name (URN) functions like a person's name, while a Uniform Resource Locator (URL) resembles that person's street address. In other words: the URN defines an item's identity, while the URL provides a method for finding it.

URLs

A URL is a URI that, in addition to identifying a web resource, specifies the means of acting upon or obtaining the representation of it, i.e. specifying both its primary access mechanism and network location. For example, the URL http://example.org/wiki/Main_Page refers to a resource identified as /wiki/Main_Page whose representation, in the form of HTML and related code, is obtainable via HyperText Transfer Protocol (http) from a network host whose domain name is example.org.

JavaScript

JavaScript (/ˈdʒɑːvəˌskrɪpt/) is a high-level, dynamic, untyped, and interpreted programming language. It has been standardized in the ECMAScript language specification. Alongside HTML and CSS, it is one of the three essential technologies of World Wide Web content production; the majority of websites employ it and it is supported by all modern Web browsers without plug-ins. JavaScript is prototype-based with first-class functions, making it a multi-paradigm language, supporting object-oriented,imperative, and functional programming styles. It has an API for working with text, arrays, dates and regular expressions, but does not include any I/O, such as networking, storage, or graphics facilities, relying for these upon the host environment in which it is embedded.

Despite some naming, syntactic, and standard library similarities, JavaScript and Java are otherwise unrelated and have very different semantics. The syntax of JavaScript is actually derived from C, while the semantics and design are influenced by the Self and Scheme programming languages.

ECMAScript

ECMAScript (or ES) is a trademarkedscripting-language specification standardized by Ecma International in ECMA-262 and ISO/IEC 16262. Well-known implementations of the language, such as JavaScript, JScript and ActionScript have come into wide use for client-side scripting on the Web.

History

The ECMAScript specification is a standardized specification of a scripting language developed by Brendan Eich of Netscape; initially it was named Mocha, later LiveScript, and finally JavaScript. In December 1995, Sun Microsystems and Netscape announced JavaScript in a press release. In March 1996, Netscape Navigator 2.0 was released, featuring support for JavaScript.

Owing to the widespread success of JavaScript as a client-side scripting language for Web pages, Microsoft developed a compatible dialect of the language, naming it JScript to avoid trademark issues. JScript added new date methods to alleviate the Year 2000 problem caused by the JavaScript methods that were based on the Java Date class. JScript was included in Internet Explorer 3.0, released in August 1996.