Passing html values into javascript functions

Question

I was making a javascript function in which I need to confirm the input. I wrote the following code but its giving negative value i.e. "else" part even if i enter a valid value. Can some one please suggest a solution?

Html file:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Javascript App</title>
<script type="text/javascript" src="app1.js">

</script>
</head>
<body><h1 id="heading1" style="text-align:center; height:auto; width:auto; font-family:'Arial Black', Gadget, sans-serif">Determinant of a nxn matrix</h1> 
<p id="paragraph1" style="font-family:'Arial Black', Gadget, sans-serif"> This program allows you to compute the determinant of a nxn matrix</p>

<p>
Input the order of the matrix
<br />

<input type="text" maxlength="3" name="value" />
<input type="button" value="submit" onclick="verifyorder(value)" />
</p>
<p id="error"></p>
<p id="detspace"></p>



</body>
</html>

Javascript File:

function verifyorder(order){
;
    if(order>0){
        return true;
    }
    else{
        alert("Sorry, you need to enter a positive integer value, try again");
        document.getElementById('error').innerHTML="Sorry, you need to enter a positive integer value, try again"; 

    }
}

The code you posted clearly runs after the problems occurs. My guess is that you have passed in a string, not a number, but without the code calling verifyorder I can't tell. — Michael Lorton
– Michael Lorton, Commented Mar 15, 2011 at 18:01
There is nothing in your code which associates the (undefined and uninitialised) Javascript variable called "value" with a DOM element which happens to have the name "value". You need in some way to tell the Javascript to find that input element and extract its value. — Colin Fine
– Colin Fine, Commented Mar 15, 2011 at 18:03

Jon Egerton · Accepted Answer · 2011-03-15 18:09:32Z

23

Give the textbox an id of "txtValue" and change the input button declaration to the following:

<input type="button" value="submit" onclick="verifyorder(document.getElementById('txtValue').value)" />

answered Mar 15, 2011 at 18:09

Jon Egerton

41.7k11 gold badges100 silver badges130 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Malcolm Salvador Over a year ago

The better answer here, which makes use of the function's arguments.

BenMorel · Accepted Answer · 2014-06-17 09:17:50Z

5

Here is the JSfiddle Demo

I changed your HTML and give your input textfield an id of value. I removed the passed param for your verifyorder function, and instead grab the content of your textfield by using document.getElementById(); then i convert the str into value with +order so you can check if it's greater than zero:

<input type="text" maxlength="3" name="value" id='value' />
<input type="button" value="submit" onclick="verifyorder()" />
</p>
<p id="error"></p>
<p id="detspace"></p> 

function verifyorder() {
        var order = document.getElementById('value').value;
        if (+order > 0) {
            alert(+order);
            return true;
        }
        else {
            alert("Sorry, you need to enter a positive integer value, try again");
            document.getElementById('error').innerHTML = "Sorry, you need to enter a positive integer value, try again";
        }
    }

edited Jun 17, 2014 at 9:17

BenMorel

37k52 gold badges208 silver badges339 bronze badges

answered Mar 15, 2011 at 18:04

KJYe.Name

17.2k5 gold badges51 silver badges63 bronze badges

1 Comment

jboxxpradhana Over a year ago

how if I want to bring param to the javascripts? javascript: somefunc(someparams); like this?

Derrick · Accepted Answer · 2017-05-31 12:50:18Z

0

Simply put id attribute in your input text field -

<input type="text" maxlength="3" name="value" id="value" />

answered May 31, 2017 at 12:50

Derrick

4,5695 gold badges41 silver badges54 bronze badges

Comments

Diodeus - James MacFarlane · Accepted Answer · 2011-03-15 18:03:56Z

-3

Try: if(parseInt(order)>0){....

answered Mar 15, 2011 at 18:03

Diodeus - James MacFarlane

115k33 gold badges164 silver badges180 bronze badges

Collectives™ on Stack Overflow

Passing html values into javascript functions

4 Answers 4

1 Comment

1 Comment

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

1 Comment

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related