Javascript Tutor - Lesson 2 Variables.


What's a variable?

Let's suppose x=5.
x is a variable. At the time of the statement, x happens to be 5. Can x be something else? Sure, x=6. Now x equals 6. (Hence the name "variable"... it's value can vary.)
Can a variable be something other than a number? Sure. How about x="Joe". Now x equals the string "Joe". (A string by the way is a string of characters).

Can the name of a variable be something other than a letter like x? Sure, myname="Joe". Simple.
How can we incorporate this new found knowledge into our function? Easy...

<HTML>
<HEAD>
<TITLE></TITLE>

<SCRIPT language="javascript"><!--

function HelloWorld()
{
myname = "Joe";
alert (myname);
}
//--></SCRIPT>
</HEAD>
<BODY>
<A HREF="javascript:HelloWorld()">Hello</A>
</BODY>
</HTML>



Try it.

(Note the first example had quotes around the string in the alert command*, but when we used a variable, there were no quotes.)
*Technically it's the alert method, but we'll get into that later. Command is fine for now and is probably a better description anyway :-)

We could make it say Hello + variable...

<HTML>
<HEAD>
<TITLE></TITLE>

<SCRIPT language="javascript"><!--

function HelloWorld()
{
myname = "Joe";
alert ("Hello " + myname);
}

//--></SCRIPT>

</HEAD>
<BODY>

<A HREF="javascript:HelloWorld()">Hello</A>

</BODY>
</HTML>

Try it..........


  Next>>  
 
Lesson Intro 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25