validate form JavaScript

Question

I'm trying to validate some of the field in my form.

and I want to check if they have input the correct area code of the required field.

The area code should be one of 212, 313, or 414

This is homework so I can't use regular expression, and I'm not really asking for an answer but here is what I'm trying to use but non of them really worked for me

if (input.substr(0,2) != 212|| input.substr(0,2) != 313 || input.substr(0,2) != 414)
                Message += " <p>Sorry but you have enter wrong area code!!!</p>";

I've tried used substring indexOf but really I don't know non of them really correct in this case.

Is there anyway to validate but not with the regular expression?

Thanks

have you tried to make sure input has a value? try calling alert(input) and see what happens. — K Mehta
– K Mehta, Commented Apr 1, 2012 at 23:45
The main problem is that substring(0, 2) only gives you 2 characters. Not three. But you should also switch the comparisons to strings and use !== — AutoSponge
– AutoSponge, Commented Apr 1, 2012 at 23:52
@KshitijMehta Yes the value I get was correct and I can validate the rest of the code except to make sure if the area code is correct. — Ali
– Ali, Commented Apr 1, 2012 at 23:54
@AutoSponge thanks for pointing out that and that was one of the problem :D — Ali
– Ali, Commented Apr 2, 2012 at 0:04

Jared Farrish · Accepted Answer · 2012-04-02 00:26:50Z

1

<input type="text" id="num"/>
<div id="msg"></div>

// This should run in a window.onload or $(document).ready() block
var num = document.getElementById('num'),
    msg = document.getElementById('msg');

num.onblur = function(){
    var areacodes = '212|313|414|',
        areacode = this.value.replace(/[^0-9]/, '').substring(0,3),
        message = 'Area code validates.';

    if (areacode.length < 3 || areacodes.indexOf(areacode + '|') === -1) {
        message = "Sorry but you have entered an invalid area code.";
    }

    msg.innerHTML = message;
};

http://jsfiddle.net/userdude/gfJWX/1

input I'm guessing is a string variable, and not a DOM note pointing to an input element.

edited Apr 2, 2012 at 0:26

answered Apr 1, 2012 at 23:47

Jared Farrish

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5 Comments

Ali Over a year ago

Yes input was just the name I assign from the field value, EDIT I tested and it doesn't work :(

Ali Over a year ago

I found out that the problem was (0,2) it suppose to be (0,3)

Jared Farrish Over a year ago

Yes, it should be three. I also added a normalizer for non-numeric characters: jsfiddle.net/userdude/gfJWX

Larry Battle Over a year ago

How is this the answer when he said "This is homework so I can't use regular expression,"?

Jared Farrish Over a year ago

@LarryBattle - The validation itself has nothing to do with regular expression, I added that to demonstrate a point that (212) wouldn't validate, although many would enter this. I also noticed I had the regex at the wrong spot. Technically, remove it and it will still "work", just won't match all forms of an entered area code.

Chibuzo · Accepted Answer · 2012-04-02 00:07:43Z

1

Try this

if (input.substr(0,3) != 212|| input.substr(0,3) != 313 || input.substr(0,3) != 414)
      Message += " <p>Sorry but you have enter wrong area code!!!</p>";

I didn't test it though

edited Apr 2, 2012 at 0:07

answered Apr 1, 2012 at 23:40

Chibuzo

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4 Comments

K Mehta Over a year ago

Why is the first argument of substr increasing? input can be one of 212, 313, or 414.

Ali Over a year ago

I'm guessing that your code will validate 313 and 414 in a wrong position the area code will only be from index 0-2

Chibuzo Over a year ago

I thought the values should be entered at once, I've edited it.

Ali Over a year ago

@Chibuzo thanks but once I tried it still doesn't work I don't know why.

Larry Battle · Accepted Answer · 2012-04-02 00:27:11Z

0

Shouldn't this work?

var str = input.trim().substr(0,3);
if ( !{212:1, 313:1, 414:1}[ str ] ){
    Message += " <p>Sorry but you have enter wrong area code!!!</p>";
}

answered Apr 2, 2012 at 0:27

Larry Battle

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