Javascript with html form validation not working

Question

i'm trying to validate a form using a simple javascript script however it is not working, can anyone tell me what is wrong with my code? (sorry for my vague question)

JS code:

<script type="text/javascript">
function validation()
{                                 
    var fName=document.forms["teacherReg"]["firstname"].value;
    var lName=document.forms["teacherReg"]["lastname"].value;
    var uName=document.forms["teacherReg"]["username"].value;
    var pWord=document.forms["teacherReg"]["password"].value;
    var cPWord=document.forms["teacherReg"]["confirmpassword"].value;

    if (fName="" || lName="" || uName="" || pWord="")
    {
        alert("Not a valid entry");
        return false;
    }

}
</script>

html form:

<form name="teacherReg" action="" method="POST" onsubmit="return validation();">
    1. First name:
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    2. Last name:<br/><input type="text" name="firstname" id="firstname" />
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    <input type="text" name="lastname" id="lastname" /><br/><br/>                             
    3. Desired Username:
    <br/><input type="text" name="username" id="username" /><br/><br/>
    4. Desired Password:
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    5. Confirm Password:<br/><input type="password" name="password" id="password" />
    &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
    <input type="password" name="confirmpassword" id="confirmpassword" /> <br/><br/>
    <center><input type="submit" value="Register" name="submitbutton" class="button" /></center>
</form>

I expect it to return false if any of the fields "fName, lName, uName, pWord" are blank, however it is always returning true

You should tell us what did you expect and what happened? why do you think it is not working? etc.. — user2203117
– user2203117, Commented Feb 14, 2014 at 9:11

dfsq · Accepted Answer · 2014-02-14 09:13:53Z

5

The problem is that you confused = (assignment operator) operator with == (comparison operator):

if (fName = "" || lName = "" || uName = "" || pWord = "") {

It should be

if (fName == "" || lName == "" || uName == "" || pWord == "") {

Fixed demo: http://jsfiddle.net/49xDH/

answered Feb 14, 2014 at 9:13

dfsq

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Comments

jvrdelafuente · Accepted Answer · 2014-02-14 09:20:51Z

1

This is the problem:

 if (fName=="" || lName=="" || uName=="" || pWord=="")

answered Feb 14, 2014 at 9:20

jvrdelafuente

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Comments

Nishant Nawarkhede · Accepted Answer · 2014-02-14 09:19:28Z

0

= is assignment operator , where == is comparison operator. use == for comparing values.

answered Feb 14, 2014 at 9:19

Nishant Nawarkhede

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Comments

digitalextremist · Accepted Answer · 2014-02-14 09:22:13Z

0

Use the comparison operator == instead of the assignment operator =.

edited Feb 14, 2014 at 9:22

digitalextremist

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answered Feb 14, 2014 at 9:20

uhs

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2 Comments

Peter Over a year ago

you shouldn't duplicate an already given answer without any added value

uhs Over a year ago

Yeah by the time i started typing ,an answer was posted .Its not my fault.Sorry bro..

Gordon · Accepted Answer · 2014-02-14 09:27:11Z

-3

Please try to use the ID instead of the form object.

function validation(){
    var username = document.getElementById('username').value;
    // etc.
}

edited Feb 14, 2014 at 9:27

Gordon

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answered Feb 14, 2014 at 9:14

Vadorequest

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3 Comments

Vadorequest Over a year ago

It also looks like your validation is wrong. if (!fName || !lName || !uName || !pWord)

Peter Over a year ago

@Vadorequest : This answer has nothing to do with the problem

Vadorequest Over a year ago

It's better to use the ID than the document form. Clean. His code was badly indented, hard to understand and wasn't following stackoverflow presentation rules.

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Javascript with html form validation not working

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Fixed demo: http://jsfiddle.net/49xDH/

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Fixed demo: http://jsfiddle.net/49xDH/

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