Dev Chunks

JavaScript Tips and Tricks

jeremyjones — Wed, 23 Mar 2011 01:54:27 +0000

JavaScript is a functional scripting language that is mainly in use as a language for running client-side scripts in a web browser. It is also common in other applications outside of web pages including PDF documents and desktop widgets. The launch of faster JavaScript virtual machines has lead to an increase in the use in [...]

Iteration

jeremyjones — Tue, 22 Mar 2011 11:53:28 +0000

If you have come to JavaScript from a background in Java or C, then you will like the variation on the for loop. It is like the for loop in Perl, Python or PHP but with a little twist. You can use a for loop to repeatedly run a block of script, or once for [...]

Context Object Manipulation

jeremyjones — Mon, 21 Mar 2011 11:11:05 +0000

One of the key concepts of JavaScript is the keyword, this, which signifies the JavaScript context object. If you write an inner function, you can access any local variables that you define in the outer function exactly as if you had defined them locally. You can also access any arguments that you pass to a [...]

Polymorphic Functions

jeremyjones — Mon, 21 Mar 2011 07:22:19 +0000

It is possible to define multiple functions with the same name in JavaScript, and the last one of those that you define will be the one that runs. This is unlike other languages where you can distinguish between functions by using a different number of arguments when you call the function. Most programmers will only [...]

Anonymous functions

jeremyjones — Mon, 21 Mar 2011 03:51:48 +0000

JavaScript allows the use of anonymous functions with full closures. Functions are objects and you can pass them as arguments just like any other object. The scope of a function includes all the names in the scope where it was declared. As you declare functions at run time and local variables can remain after the [...]

Type Conversion

jeremyjones — Sun, 20 Mar 2011 11:51:20 +0000

JavaScript has member functions for all objects, such as valueof and toString. When you use literal numbers, Booleans, strings, undefined and null are different from the counterparts that you use for objects. This example shows this: <br /> Typeof new Number(i); // Returns object<br /> Typeof I; // Returns number<br /> There are ways that [...]

Objects and Associative Arrays

jeremyjones — Sun, 20 Mar 2011 09:59:42 +0000

The JavaScript Object is very versatile and useful. It works a little like the Object base type in Java and the associative array type like %hash from Perl, dict from Python or array from PHP, and is the best of both worlds. You can also use them for String to Object mapping. You can initialize [...]

Using Firebug

jeremyjones — Sun, 20 Mar 2011 04:50:06 +0000

JavaScript is easy to write, but can be difficult to debug effectively due to the limited debugging functionality it provides. One big difficulty is the lack of an effective way to display debugging messages. You can overcome these limitations with the help of external debuggers. If you are developing JavaScript code for the Firefox browser, [...]

Null, Undefined and Delete

jeremyjones — Sat, 19 Mar 2011 09:49:33 +0000

Unlike most other programming languages, you can use both undefined and null values in JavaScript. This can be confusing for someone who comes to JavaScript from another programming language. When an object is undefined, it means that it has still to be declared or has been declared and not given a value. Null is a [...]

Assertion

jeremyjones — Sat, 19 Mar 2011 06:49:06 +0000

Assertion is one of the common techniques that people use to debug JavaScript code. You use assertion to ensure that an expression evaluates to true during script execution. This means that if any expression evaluates to false there is possibly a bug in your code. There is no inbuilt assert function in JavaScript, but it [...]