Tutorial Empty an Array

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This is one of the fastest and easiest ways of emptying an array. Of course there are may other ways, but those usually include creation of a new array. This way you reuse the same array.

var myArray = ["one", "two", "three"];

// console.log( myArray ) => ["one", "two", "three"]

myArray.length = 0;

// console.log( myArray ) => []

Tutorial Different Stylesheets for Different Days of the Week

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<script type="text/javascript">
<!--
dayNames = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
dayNumber = new Date().getDay();
document.writeln('<link rel="stylesheet" type="text/css" href="' + dayNames[dayNumber] + '.css">');
//-->
</script>

<noscript>
<link rel="stylesheet" type="text/css" href="default.css">
</noscript>

Name your css files accordingly: Saturday.css, Friday.css, Sunday.css, etc...

If JavaScript is disabled in the browser, it will revert back to the default.css file.

Tutorial Different Stylesheet Pending the Time of Day

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<script>
<!--
function getStylesheet() {
      var currentTime = new Date().getHours();
      if (0 <= currentTime&&currentTime < 5) {
       document.write("<link rel='stylesheet' href='night.css' type='text/css'>");
      }
      if (5 <= currentTime&&currentTime < 11) {
       document.write("<link rel='stylesheet' href='morning.css' type='text/css'>");
      }
      if (11 <= currentTime&&currentTime < 16) {
       document.write("<link rel='stylesheet' href='day.css' type='text/css'>");
      }
      if (16 <= currentTime&&currentTime < 22) {
       document.write("<link rel='stylesheet' href='evening.css' type='text/css'>");
      }
      if (22 <= currentTime&&currentTime <= 24) {
       document.write("<link rel='stylesheet' href='night.css' type='text/css'>");
      }
}

getStylesheet();
-->
</script>

<noscript><link href="main.css" rel="stylesheet"></noscript>

Name your css files accordingly: night.css, day.css, etc... One cool bonus is that since JavaScript gets the time from the local machine instead of from the server, users will be served the time-based stylesheet based on their time, not the server's, which may be in a completely different timezone.

If JavaScript is disabled in the browser, it will default to the main.css stylesheet.

Tutorial Detect Javascript On/Off, With Notification

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<script type="text/javascript">
   document.write("Welcome, you have Javascript on.")
</script>

<noscript>JavaScript is off. Please enable to view full site.</noscript>

If JavaScript is on the user gets a welcome message. If off, the user is instructed to turn it on.

Tutorial Detect Internet Explorer

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<script type="text/javascript">

if (/MSIE (\d+\.\d+);/.test(navigator.userAgent)) { //test for MSIE x.x;
 var ieversion=new Number(RegExp.$1) // capture x.x portion and store as a number
 if (ieversion>=8)
  document.write("You're using IE8 or above")
 else if (ieversion>=7)
  document.write("You're using IE7.x")
 else if (ieversion>=6)
  document.write("You're using IE6.x")
 else if (ieversion>=5)
  document.write("You're using IE5.x")
}
else
 document.write("n/a")

</script>

Reference

Tutorial Default Arguments for Functions

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// Combiner of passed arguments and defaults (usable with any function)
Object.prototype.combine = function(_args){
  for(var i in this) {
    if(typeof _args[i] == "undefined") {
      _args[i] = this[i];
    }
  }
};

// Specific example function with defaults
function feedTheCat(args){
  var defaults = {
      'morning' : "nothing",
      'noon'    : "pork",
      'nite'    : "mouse"
  };
  defaults.combine(args);
}

// USAGE: only passing 2 of 3 arguments
feedTheCat({
  'morning': "milk", 
  'nite': "kitekat"
}); 

// Values would be: milk | pork | kitekat

Reference URL

Tutorial Current Page with JavaScript

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This is like a replacement for PHP's SCRIPT_NAME with JavaScript.

location.href.split('/').pop();

For example with this URL:

http://css-tricks.com/examples/ScriptName/index.php

This code:

document.write( location.href.split('/').pop() );

Would write to the page: "index.php"

Reference URL