javascript validation with an array

Question

I wrote a javascript function to validate that the user input data is not empty. The function called "isNotEmpty()" identifies that the text box is empty. But however the main function returns a true statement to the JSP page. Thus the form gets submitted.

The alert no 2&3 fires according the input from the form. but the Alert No1 dose not fires in any circumstances.

Please check on this and assist me. Thank you.

var firstName;
var data  = new Array(); 

function formEntryValidationTest() {
    firstName = document.forms["regForm"]["firstName"];
    data[0] = isNotEmpty(firstName);//check the first name is empty

    for(var i=0;i<data.length;i++) {
        if(data[i]=="false")
        {
            alert("Check"); //alert No-1
            return false;
        }
    }
}

// this is the function to check whether the input is not empty
function isNotEmpty(obj) {
    if(obj.value!="") {
        alert("true"); //alert No-2
        return "true";
    }
    else
    {
        alert("false");//alert No-3
        return "false";
    }
}

It works for me: jsbin.com/ozalan/1/edit

Jason Orendorff
– Jason Orendorff

2012-09-08 14:27:18 +00:00
Commented Sep 8, 2012 at 14:27 — Jason Orendorff
– Jason Orendorff, Commented Sep 8, 2012 at 14:27

Brandan · Accepted Answer · 2012-09-08 14:06:06Z

4

You're returning the string "false" rather than the boolean value false, which in JavaScript evaluates to a "truthy" value.

Change the return statements in isNotEmpty to return true; and return false; and the condition in formEntryValidationTest to if (!data[i]).

Also, the condition you check in isNotEmpty is too strict. It will return true for undefined and null, which may be the reason your code isn't working. Change it to something like this:

function isNotEmpty(value){
  return value ? value.length > 0 : false;
}

Then pass the input value directly rather than passing the input object itself:

data[0] = isNotEmpty(firstName.value);

edited Sep 8, 2012 at 14:06

answered Sep 8, 2012 at 13:33

Brandan

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4 Comments

Sumer Over a year ago

No generally in the form onSubmit, I calls the formEntryValidationTest() function.

Sumer Over a year ago

I changed the source code according to your instructions, no improvement.

Sumer Over a year ago

I found a clue. When I commented the "data[0] = isNotEmpty(firstName.value)" and changed the condition as "if(!isNotEmpty(firstName.value))", it worked perfectly. Meanwhile I taken-off the comment which I mentioned here same problem occurred. Can you say why is it?

Sumer Over a year ago

Here are my files. You'll find error even I made the changes according your instructions. I don't know why. Please refer the link mediafire.com/?9kac6352z6749z0

iRadio · Accepted Answer · 2012-09-08 13:46:47Z

1

You are using strings "true" and "false" instead of boolean values true and false. Remove the quotes as in:

   return true

instead of 

   return "true"

Do the same in your if statement:

    if(data[i]==false)
instead of
    if(data[i]=="false")

(Note that there are no quotes)

answered Sep 8, 2012 at 13:46

iRadio

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1 Comment

Sumer Over a year ago

I did but the issue remains same.

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