Reading string with javascript

[TurboSRT4]

hello, I am fairly new to javascript and this is really the first dynamic site I am attempting. I am good with perl and thats it. I have noticed with javascript examples they return true or false........ what exactly does the value "true" or "false" get returned to? is it assigned a variable name?

I am wondering a simple way to check if a var is a certain amount of digits like 10 for phone number and 5 for zip code.

please see the registration page here iboost.biz

when you submit the form it calls a function which returns the eroors in a popup box as you will see. The phone number is set as var p_num without calling another function what is a simple if statement to see if p_num is 10 digits. I already have it only accepting numbers.

if (p_num ???????????){
my_errors = my_errors + "Phone Number Must Contain 10 Digits";
}

thanks guys!

[BlaineSch]

When something is returned if it's not assigned or done something with its return value is gone forever.

<scriopt>
function find() {
return "134";
}
document.write(find());
if(find()=="134") {
document.write("Yes!");
}
var findvar = find(); 

[TurboSRT4]

Thank you that was a very simple and very useful explanation it makes a lot of sense. Any help with my question about containing a certain amount of digits or characters?

[BlaineSch]

Yes

<script>
var mystring1 = "hello world";
document.write(mystring1.length);
</script> 

[TurboSRT4]

im sorry man i dont quite understand that.....

say i have....
<script>
function register(){
var p_num = document.register.phone.value;
if (p_num ????????){
var error = "invalid phone number";
}
}
</script>

i need it to return var error with invalid phone number if it does not contain exactly 10 digits. I have googled it but get complicated and not straight forward answers. I just need something simple thanks

[BlaineSch]

<script>
function register() {
    if(document.register.phone.value.length != 10) {
        document.write("Invalid phone number.");
        return false;
    }
    return true;
}
</script> 

[TurboSRT4]

thanks a lot man

[TurboSRT4]

lol sorry can you please explain what the hell return true and false does! I dont get it what is the point of returning true and false and how do u tell if it was returned true or fals lol sorry might sound like a dumb question but it would reallly explain a lot! thanks

[BlaineSch]

Depending on how your using you this you may not need it. If this was in the "submit" button and it returned false in it's "onclick" I believe it will not allow you to submit the form which is what you want.

True/false is boolean values. If you returned "register()" you could test if it's true or false"

<script>
function register() {
    if(document.register.phone.value.length != 10) {
        document.write("Invalid phone number.");
        return false;
    }
    return true;
}
if(register()) {
    document.getElementById('errors').innerHTML = "Correct value!";
}
</script> 

[TurboSRT4]

gotcha thanks again man