Javascript Dynamic Variable (Random number addded)

My question is, how do I create a dynamic variable in Javascript?

For example, I have:

var myAwesomeText = "Hello World!"

But now I want the varible MyAesomeText to have a random number attached to it every time the page is refreshed. So it would instead look like something like this:

var myAwesomeText12345 = "Hello World!"

And most importantly, how do I call that that new random variable back once the random number has been assigned to it? (i.e: alert(???);)

I've tried something like this, but I'm going wrong with this somewhere.

var myRnd = Math.floor(Math.random()*100000);
var myVar = "MyAwesomeText" + myRnd;
str = myVar + ' = ' + '"Hello World!"';
eval(str);

alert(str);

Any help is much appreciated.