javascriptcheatsheet

javascriptcheatsheet - JavaScript cheat sheet Holmer Hemsen...

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Unformatted text preview: JavaScript cheat sheet Holmer Hemsen NISLab University of Southern Denmark November 1, 2002 1 JavaScript Document Template A JavaScript can be included both in the header and/or the body of the document, the choice depends on the task. There can be several JavaScripts in a document. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>JavaScript Template</title> <script language="javascript" type="text/javascript"> <!-- Hide script from old browsers /* * Author: Firstname Lastname <email> * Date: * Version: * Last modified: * * Purpose: Description of the problem the program was written to solve. * Known Bugs: */ // End hiding script from old browsers --> </script> <noscript> <b>You dont have JavaScript enabled or your browser does not support JavaScript</b> </noscript> </head> ... 1 2 Semicolons, whitespace and case sensitive In JavaScript semicolons are optional. Use them anyway, it is more secure! Whitespaces are ignored by JavaScript, unless as part of a String (e.g. I like JavaScript) and for separating keywords, variable names, numbers and functions. JavaScript is case sensitive, that means: bgColor is not equal to bgcolor . 3 Comments 3.1 Single-line comment // e.g. to comment the meaning of a variable 3.2 Multiple-line comment /* e.g. to comment purpose and parameters of a function * Function: saySomething * Purpose: displaying a message in an alert box * Parameters: * message: the string to be displaying in the alert box * Return: The return value of this function is void * (no return value) * Side Effects: This function changes no global variables. */ 4 Variables 4.1 Variable assignment Using var outside of function is optional. Assigning variables using var inside of functions is required if (a) we want to declare a local variable and a global variable with the same name already exists.(b)If recursive functions use variables with the same name. x = 42; var x = 42; 4.2 Variable scope Variables in JavaScript have in general global scope. However, variables assigned inside of functions have function-local-scope. Take care, if you define a local variable in a function and a global variable with the same name exists, the global variable is not visible any more inside the function, no matter where you define the local variable....
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This note was uploaded on 04/29/2010 for the course CS 5503 taught by Professor Kaylor during the Spring '10 term at W. Alabama.

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javascriptcheatsheet - JavaScript cheat sheet Holmer Hemsen...

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