JavaScript is a scripting language developed by Brendan Eich of Netscape. It was first called Mocha. Then the name changed to LiveScript, then later to JavaScript. It was first deployed in the Netscape browser in 1995 and was quickly established as a successful client-side scripting language for web pages. The success of JavaScript sparked Microsoft into creating a compatible dialect which they named J-Script. In 1996, Microsoft included Jscript in their release of Internet Explorer 3.0. Netscape submitted JavaScript to EMCA International for consideration to become industry standard and a standardized version, EMCAScript was introduced.
JavaScript is now one of the most popular programming languages for web pages. It was at first looked down on by industry professionals as it was targeted at less-experienced developers but when Ajax programming came into prominence this put JavaScript back into limelight and it began to grow and gain professional respect. JavaScript usage increased and it began to be used outside of web browsers, resulting in the CommonJS project in being founded in 2009. The common JS project established a standard library for outside of the browser JavaScript development.
Using JavaScript, a programmer can design interactive pages. The script language can interact with HTML source code to enable dynamic content. JavaScript statements are imbedded into an HTML page. The statements then recognise an action by the user, such a mouse click or input in a form and then trigger the necessary response to that action. JavaScript functions are often used to verify that a user has entered the correct information into a form field and if not, it could bring up an alert or prevent further progression until the information in the form has been input correctly. JavaScript can also be used to perform an action, such as playing an audio file when a user visits a particular page.
Any developer who knows how to write HTML can create responses to actions performed by the user through JavaScript. This could include the changing of images as the mouse moves over them, playing different sounds in response to specified events, opening up a new window and controlling the size and position of the window and the attributes within that window, such as whether toolbars and menus are visible.