Fire JavaScript function from html button

Question

I have a html form where on button click, JavaScript function needs to start and a new row in a table needs to be inserted. How can I assemble the JavaScript code properly?

Here is the code:

<SCRIPT language="javascript">       
    function addRow()
    {
var table = document.getElementById('table');

var button = document.getElementsByTagName('input')[0];

button.onclick = function() {
    var clone = table.rows[table.rows.length - 2].cloneNode(true);
    clone.cells[0].firstChild.data =
        clone.cells[0].firstChild.data.replace(/(\d+):/,function(str,g1) {
                                                           return (+g1 + 1) + ':';
                                                        });
    table.tBodies[0].appendChild(clone);
};
 }
    </SCRIPT>

and the html part:

<input type=button value='Change' onclick="addRow" />
<br /><br />
<table cellspacing=0 cellpadding=4 id="table">
<tbody>
<tr><td>Number 1:</td><td><input value=20 style="width:30px" type=text  maxlength=2/></td></tr>
<tr><td>Number 2:</td><td><input value=25 style="width:30px" type=text  maxlength=2/></td></tr>
<tr><td style="border-top:solid 1px black;border-bottom:solid 1px black;">Sum:</td><td style="border-top:solid 1px black;border-bottom:solid 1px black;"><div>45</div></td></tr>
</tbody>
<tfoot>
<tr><td style="border-top:solid 1px black;border-bottom:solid 1px black;">Sum:</td><td style="border-top:solid 1px black;border-bottom:solid 1px black;"><div>45</div></td></tr>
    </tfoot>
</table>

"button" is a reserved word in JavaScript. Rename it to another variable. See: javascripter.net/faq/reserved.htm — Diodeus - James MacFarlane
– Diodeus - James MacFarlane, Commented Jan 13, 2012 at 16:32

Brandon · Accepted Answer · 2012-01-13 16:32:40Z

1

<input type=button value='Change' onclick="addRow" />

addRow is a function. When you're calling a function like this, you need to add the (). Also, you should wrap button in quotes as it is an attribute value.

Change it to

<input type="button" value="Change" onclick="addRow()" />

jsFiddle example

answered Jan 13, 2012 at 16:32

Brandon

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2 Comments

Quentin Over a year ago

@Zee — Yes it is. Not best practice, but certainly valid.

Zee Spencer Over a year ago

You're right. XHTML 1.0 strict doesn't like onClick, but HTML5 accepts it.

Zee Spencer · Accepted Answer · 2012-01-13 16:48:15Z

1

Javascript uses an event based architecture.

I would recommend investigating jQuery's bind function. If you are dealing with elements which are dynamically added/removed from the page, I would recommend the "on" function instead.

edited Jan 13, 2012 at 16:48

answered Jan 13, 2012 at 16:37

Zee Spencer

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1 Comment

Stefan Over a year ago

That´s good but the live() function is obsolete and replaced by on().

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