Essential Javascript -- A Javascript Tutorial

By Patrick Hunlock
2007-12-02


JavaScript Loops: FOR

The for loop follows basic C syntax, consisting of an initialization, an evaluation, and an increment.

for (var i=0; (i<5); i++) {
   document.writeln('I is equal to '+i+'<br>');
}
// outputs:
// I is equal to 0
// I is equal to 1
// I is equal to 2
// I is equal to 3
// I is equal to 4

This is actually an extreme simplification of what a for statement can do. On the other end of the spectrum, consider this shuffle prototype which will randomly shuffle the contents of an array. Here, everything is defined, and executed within the context of the for statement itself, needing no additional block to handle the code.

Array.prototype.shuffle = function (){ 
   for(var rnd, tmp, i=this.length; i; rnd=parseInt(Math.random()*i), tmp=this[--i], this[i]=this[rnd], this[rnd]=tmp);
};

Tutorial Pages:
» Essential Javascript -- A Javascript Tutorial
» Getting Started
» In-Line Javascript
» External Javascript
» Javascript is case sensitive
» Output (writeln)
» Output (alert)
» Output (getElementById)
» Input (One Click To Rule Them All)
» Input (User Input)
» Javascript is an Event Driven Language
» Comments
» Variables
» Variable Scope
» Special Keywords
» Arithmetic Operators
» Logical and Comparison Operators
» JavaScript Conditionals: IF
» JavaScript Conditionals: SWITCH
» JavaScript Conditionals: Shorthand Assignment
» JavaScript Conditionals: Ternary Operators
» JavaScript Loops: FOR
» JavaScript Loops: FOR/IN
» JavaScript Loops: WHILE
» Bringing It All Together
» DHTML: Dynamic HTML
» Conclusion


copyright © 2006, 2007 by Patrick Hunlock

Related Tutorials: » JavaScript Debugging Techniques with Firebug » Striped Tables Using JavaScript » Opening PDFs in a New Window with JavaScript » Submit Forms Conditionally using JavaScript » How to Setup a Randomising Function » Introduction to JavaScript Tutorial