Monthly Archive: April 2012

Summary of what JavaScript (JS) is and is not;

• JS is a client-side, object-based, case-sensitive language. Whose interpreter is embedded  in the web browser software.
• Variable names, function names must avoid JS keywords, reserved words and object names.
• For JS code each opening HTML <script> tag must assign a MIME type of “text/javascript” to its type attribute
• Script block can have single line or multiple line comments
• Each JS statement must end with a semicolon.
• Inline JS code can be assigned to any HTML event attribute such as onload, or enclosed within a <script> element in the document body section.
• All JS code is best located in an external file whose source is specified to a src attribute of the <script> tag.
• Unobtrusive JS places all script code in an external file and can specify a function to the window.onload DOM property to set behaviours when the HTML document loads.
• JS variables are declared using the var keyword and can store any datatype – boolean, number, string, function or an object.
• JS functions are declared using the function keyword. and the function name must have trailing parentheses followed by a pair of braces {} enclosing statements to execute.
• A function declaration may specify arguments within its trailing parentheses that must be passed from its caller.
• A value can be returned to the caller using the return keyword.
• Local variables declared inside a function are only accessible within that function.
• Global variables declared outside functions are accessible from within any function within that script.

Source: JavaScript in Easy Steps