JavaScript Lesson 1 - Javascript Variable and Function Identifier Valid Characters

This Lesson's Goal

Teach that the variable or function identifiers in Javascript can be just about anything including characters like $, _, . (periods), and more...

References On The Net

Search the net for the latest EMCA Javascript standards and you will learn that just about any character can be used as a Javascript identifier, noting however that the EMCA standard suggests that the $ and _ should be associated with machine generated code. It is common though that developers use these freely in their code and most prevalent latetly that a $(id) function replaces the document.getElementById(id) syntax to provide shorthand during coding and potentially improves readability of the code as well. The $ sign is used in most programming languages as a "dereferencing" character for compilers and parsers and makes a convenient dereferencing character for Javascript functions as well. It is however totally convention and the $ character is only special in the minds of humans and not any more special than any character to the computer...

The Demo

Click the button below and the following function will be run. It will call the oddly named functions shown in the script to prove you can use such names in your own variable and function names.

Work success tip

Your team lead and development group standards wherever you work should be explored early in your new assignments. The standards documented or practiced by convention should outline the conventions that you should use for variable and function naming conventions. Do not run off on your own without asking if a convention exists, read some other senior developers programming code to see their style, and mimic it as closely as possible while adhering to or improving upon that work to be in line with the team's documented standards. In other words, when in rome, do as they do, and that adage clearly applies to development teams you may become a part of. Try and do as the rest of the team members are accustomed to as that will help them read or repair your code and you to read and support or repair theirs.

The Script for this Lesson

<script type = "text/javascript"> function runDemo() { // Define function objects var func1 = function() { alert("hello from func1"); } func1.func2 = function() { alert("hello from func1.func2"); }; var _ = function() { alert("hello from _"); } var \u0024 = function() { alert("hello from $ defined as u0024"); } var Ø = function() { alert("hello from Ø"); } var $$$$$ = function() { alert("hello from $$$$$"); } var $func$ = function() { alert("hello from $func$"); } var __ = function() { alert("hello from __"); } _.$ = function() { alert("hello from _.$"); } __.__ = function() { alert("hello from __.__"); } $.member = function() { alert("hello from $.member"); } // Call functions defined above one by one func1(); func1.func2(); _(); $(); Ø(); $$$$$(); $func$(); $.member(); _.$(); __(); __.__(); } </script>

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