HTML Goodies: Script Tip: Week 11

www.htmlgoodies.com/beyond/javascript/stips/article.php/3471431

HTML Goodies: Script Tip: Week 11
By Joe Burns
January 4, 2005

Hey, Tip Types...
Let's tear this one apart. Today we're going to look at a rather small but quite important command, the equal sign.
Let's take a quick look at the script again:

<SCRIPT LANGUAGE="javascript">

</SCRIPT>

I want you to look at two uses of the equal sign within the script:

(navigator.appname == "Netscape")
and
{parent.location="nspage.html"}
Notice the first use of the equal sign doubles it up and the second is the more traditional single equal sign. Now, to us humans, one or two equal signs don't make for a big difference, but to a JavaScript-reading computer, it signifies a great deal of difference.
Without getting into a lot of programming mumbo jumbo, here's the basic difference (and this always did seem backward to me).

A double equal sign means "is equal to."
     Notice the line above involving the double equal sign? It is saying if the navigator application name is equal to Netscape.

A single equal sign means "is."
     I'm sure there's a better way of putting it, but that's how I keep it all straight. Notice the line above that uses the single equal sign? It is saying the parent location is nspage.html.

You'll also see a single equal sign being used to denote variables and the like. Just keep it all straight by remembering that only the double equal sign means "is equal to" and the single equal sign can be roughly translated into "is."
That should help you keep it all straight, too.
Next Week: The IF/ELSE Condition

     Do YOU have a Script Tip you'd like to share? How about suggesting a Script Tip to write about? I'd love to hear it. Write me at: jburns@htmlgoodies.com

Learn to write your own JavaScripts with the
HTML Goodies 30-Step Primer Series
and take the knowledge home with you in
JavaScript Goodies!
You can find many other uses for JavaScript
on your Web pages here!