Validating a form with JavaScript with multiple variations

Question

I'm having trouble making sure that my form is completely filled out.

Here is the html:

<div id="username_input">
    <span>User name:</span> <input id="username" onclick="changeBackground('#ffffff', this.id)" type="text" name="firstname" />
    <small id="username_error_message">please input username</small>
</div><!-- End of div id username_input -->

<div id="email_input">
    <span>Email:</span> <input id="email" onclick="changeBackground('#ffffff', this.id)" type="text" name="email" />
    <small id="email_error_message">please input email</small>
</div><!-- End of div id email_input -->

<div id="textarea">
    <textarea id="textarea_body" onclick="clearTextarea()" rows="5" cols="120"></textarea>
</div><!-- End of div id textarea -->

<div id="submit_button">
    <input id="button" type="submit" name="Submit" value="Post Comment" />
</div><!-- End of div id button -->

All I'm trying to do is to make sure that a user doesn't leave an empty input.

Here is what I have so far before running into a problem:

function inputCheck() {
        /*  This is to check if the values, username - email 
            and text area body, in the input form are filled in */
        if($('username').value.length == 0 || $('email').value.length == 0 || $('textarea_body').value.length == 0) {
            if($('username').value.length == 0) {
                alert("Invalid username");
                return false;
            } else if ($('email').value.length == 0) {
                alert("Invalid email");
                return false;
            } else {
                alert("Invalid post");
                return false;
            }

        } else {
            return true;
        }

I want all three alert boxes to show up at once. The problem I'm having is that it looks at the first if statement and then breaks out of the JavaScript code.

I am later on going to have unique messages tell them "Please input email" or "Please input username" but since I can't more then one if statement I don't know how this is going to work.

I don't want to be using an js libraries.

Consider avoiding onclick attributes and set handlers using JavaScript. — Šime Vidas
– Šime Vidas, Commented Nov 7, 2010 at 0:31
P elements (paragraphs) would be more suited in your case than DIVs — Šime Vidas
– Šime Vidas, Commented Nov 7, 2010 at 0:35
Why should I avoid onclicks? What is the better replacement? — Philip
– Philip, Commented Nov 7, 2010 at 1:49

Jeremy Worboys · Accepted Answer · 2010-11-07 00:25:06Z

3

If you aren't using a Javascript library, what is $() defined as?

If it is something similar to the jQuery library then you would need to use $('#username') or document.getElementById('username') instead.

answered Nov 7, 2010 at 0:25

Jeremy Worboys

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1 Comment

Šime Vidas Over a year ago

Probably a shortcut for getElementById

Šime Vidas · Accepted Answer · 2010-11-07 00:37:28Z

0

var message = "";
if ( !$('username').value ) {
    message += "Invalid username. ";
}
if ( !$('email').value ) {
    message += "Invalid email. ";
}
if ( message === "" ) {
    message = "Invalid post.";
}

alert(message);
return false;

edited Nov 7, 2010 at 0:37

answered Nov 7, 2010 at 0:29

Šime Vidas

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1 Comment

Philip Over a year ago

That's not going to work for me, because I don't actually want to use a alert later on.

Dave Anderson · Accepted Answer · 2010-11-07 01:19:13Z

0

Your return false; statement after each alert will exit your inputCheck() function and return to the caller which I'm guessing is the Form Post event and returning false is preventing submission. This occurs after the first error found.

For a user to get multiple alert boxes they have to acknowledge for form validation isn't a great user experience. Consider building up a string with all the errors from the form and show them in one alert.

function inputCheck() {
    var errMsg = '';

    if($('username').value.length == 0) errMsg += 'Enter a valid username.\n';
    if($('email').value.length == 0) errMsg += 'Enter a valid email address.\n';
    if($('textarea_body').value.length == 0) errMsg += 'Enter an email body.\n';

    if(errMsg.length > 0) {
        alert('Please correct the following:\n' + errMsg);
        return false;
    }

    return true;
}

answered Nov 7, 2010 at 1:19

Dave Anderson

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2 Comments

Philip Over a year ago

Well, I won't actually be using an alert, i'll be changing the <small> tags. I have tried and removed the first return false but it still doesn't work.

Dave Anderson Over a year ago

@Philip You have if { } else if { } else { } so only one will check will ever be executed. You want each check to fire so they should be independent tests if { } if { } if { }.

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