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This is a summarized form of the JavaScript Tutorial.

For reference JavaScript specifications can be found here .

• JavaScript is the most popular scripting language on the internet and works in all major browsers.
• It is a lightweight, interpreted language that is embedded into webpages to add interactivity.
• JavaScript can read and write HTML page elements, react to events, validate data, create cookies.
• JavaScript was invented by Brendan Eich of Netscape but is now known officially as ECMAScript (current version is ECMA-262).
• A simple “Hello World” example

  <script type="text/javascript">
  <!--
  document.write("Hello World!");
  //-->
  </script> 

• JavaScript code may be located
  • In the head - executed when called
  • In the body - executed while loading
  • In an external file called from either the head or the body e.g. <script src=“abc.js”></script>

• JavaScript is case-sensitive.
• Statements may omit the final semi-colon but should not.
• Blocks may be grouped together using curly braces { }.
• JavaScript uses java-style comments: and /* */. * JavaScript variables are case-sensitive and must begin with a letter or underscore. * Variables are automatically declared when first used but should be explicitly declared using e.g. var a = 5; *