Posts Tagged ‘Javascript’

Include an “or” Operator in a JavaScript Switch Statement

Posted in Programing, Web Development on July 4th, 2011 by Jarred – Comments Off on Include an “or” Operator in a JavaScript Switch Statement

I came across a situation where I needed a switch statement in JavaScript to do the exact same thing in multiple cases. For example:

switch (varAnimal)
{
   case ‘dog’:
   sameFunction();
   break;

   case ‘cat’:
   sameFunction();
   break;

   case ‘bird’:
   sameFunction();
   break;
}

While the above code works, if you have a long list of variables it is highly inefficient. To solve the problem I initially tried to use an “or” operator to try and test for the different values as you would do in an “if” statement. For example:

switch (varAnimal)
{
   case ‘dog’ || ‘cat’ || ‘bird’:
   sameFunction();
   break;
}

However this didn’t work. I found on a forum the below method which appears to accomplish what I was trying to do. It essentially lets you use an “or” operator to test for multiple cases which can save a lot of typing. For example:

switch (varAnimal)
{
   case ‘dog’: case ‘cat’: case ‘bird’:
   sameFunction();
   break;
}

Source: http://www.webdeveloper.com/forum/showthread.php?t=191879

How to find the length of an associative array in JavaScript

Posted in Programing, Web Development on June 26th, 2011 by Jarred – Comments Off on How to find the length of an associative array in JavaScript

So this little tidbit took me a bit by surprise. The .length property does not work on associative arrays in JavaScript. It will return zero no matter how many elements are in the array. Below is a script I found that will correctly return the length of a JavaScript associative array.

 

associativeArrayLength = function(obj)
{
    var size = 0, key;
    for (key in obj)
        {
        if (obj.hasOwnProperty(key)) size++;
        }
    return size;
};

 

Source: http://stackoverflow.com/questions/5223/length-of-javascript-associative-array

Select random element from a Javascript Array

Posted in Programing, Web Development on June 25th, 2011 by Jarred – Comments Off on Select random element from a Javascript Array

Need to select a random element from a javascript array? The process is fairly straightforward but I was not clever enough to figure it out on my own. First take a random number with Math.random() [which will return a random number between 0 and 1] then multiply this number by the length of the array. You then need to use Math.floor to round the number down to the nearest whole number and voila… you have a random element number. All of this can be included in the square brackets of the array to make more condensed/easy to read code.

For Example

randomElement = testArray[Math.floor(Math.random()*testArray.length)];

 

 

Source: http://www.webmasterworld.com/forum91/2245.htm

How to test if a Javascript Array Is empty

Posted in All, Programing, Web Development on June 25th, 2011 by Jarred – Comments Off on How to test if a Javascript Array Is empty

Need to test if a javascript array is empty? Here is a little trick I found online. I was assuming that there was a some sort of built in function to test if the array but not so.   The trick is to check if the length of  the array is less than 1.

 

For example

if (theTestArray.length < 1)
alert (‘Array Is Empty’);

 

 

Source:http://bytes.com/topic/javascript/answers/90314-check-if-array-empty