Favorite books?

**mburt** · 09-29-2006, 02:36 PM

Okay I see your point. So you need a JavaScript book that isn't too easy, but sort of easy. Just enough to get the hang of it.
Anyways...

what for-loop is, how it works, and give an example of how it's used

Easy.
A for loop in JS is exactly the same as C++ (just isn't as strict). There's only one type of variable in JS, no int, double, etc. So. Here's a basic for-loop

Code:

for (var i = 0;i < 25;i++) {
	document.write(i)
	//display the value of "i"
	}

For-loops can be useful in verifying information, running through a sequence of arrays etc.

An array is a variable that stores data in sequence:

Code:

var myArray = ["value 0","value 1","value 2","value 3","this is another value"]

So you could say...

Code:

document.write(myArray[1])

Which would display "value 1"
Not that hard when you look at it from a glance.
So if you can store data using a decimal value, here's where your for-loop comes in.
Let's take a look at this code:

Code:

<html>
<head>
<script type="text/javascript">
function results(contestant) {
var entries = ["jonathan","damien","courtney","kyle"]
for (var i = 0;i < entries.length;i++) {
	if (contestant.value == entries[i]) {
		alert(entries[i]);
		}
	}
}
</script>
</head>
<body>
Type in the winners name:
<br><input type="text" id="winner">
<br><input type="button" value="Go" onclick="results(winner)">
</body>
</html>

The "entries" variable are all the possibilities. The for-loop runs numbers from 0 to the array "entries" length (entries.length is how many values there are in entries). If a winner is found in the input (the argument "contestant") it will alert saying the winners' name. Not too complex, just a little experiment with the for-loop.

**Eclyps19** · 09-29-2006, 02:45 PM

lol, i appreciate explaining the for-loop to me, but I already knew that =)

i just used loops as an example, since we were already talking about it in the post before.

But I wasn't sure exactly how to declare arrays, so that's a plus!

Also, I know that there is only one type of variable in javascript, but what happens if you try to add 1 variable with text to a variable with numbers? Will it result in StringNumber? or will it give you an error? Will it just flat out not work?

Hrm... this is getting a bit off topic...

**mburt** · 09-29-2006, 03:04 PM

When you add a number variable to a string, the browser defines the "+" operater as an assignment operator, not addition. So it won't try to add the string and the number, it'll just add the two on top of each other

Ex.

Code:

var a = 2
var b = "string"
document.write(b+a)

Will turn out "string2" just like that

**blm126** · 09-29-2006, 07:31 PM

Check out this book. I haven't read it yet(plan to get it soon), but if it is anything like the website is should be great. I have also read good things about this book.

**Twey** · 09-29-2006, 07:45 PM

the browser defines the "+" operater as an assignment operator

Concatenation, not assignment.

**mburt** · 10-01-2006, 01:20 AM

Concatenation, not assignment.

Ah yes, my mistake.

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