document.getElementById is returning null on the button click

Question

I have a textarea and a button. The button submits the data to a page through AJAX through a function. When the button is clicked it calls a function that takes in 3 parameters for this question only one of them is necessary.

Let's look at the code to understand more clearly:

var offers = <? php echo PostOffer::GetOffers($_GET["id"]); ?> ;
for (var i = 0; i < offers.length; i++) {
    var date = offers[i].Date.split(" ");
    document.write('<div class="row-fluid offer">' +
        '<div class="span2">' +
        '<img class="profile_picture" src="' + offers[i].Picture_Path + '" />' +
        '</div>' +
        '<div class="span10">' +
        '<div class="row-fluid">' +
        '<div class="username">' +
        '<p style="font-weight: bold;">' + offers[i].Name + '</p>' +
        '</div>' +
        '</div>' +
        '<div class="row-fluid">' +
        '<div class="content">' +
        '<p class="content">' + offers[i].Text + '</p>' +
        '<textarea class="hide span12" id="edited_content">' + offers[i].Text + '</textarea>' +
        '<button type="button" class="hide btn btn-primary btn-small" id="save_edits" onclick=\'editPostOffer("<?php echo $_GET["id"]; ?>","' + offers[i].Offer_ID + '","' + document.getElementById("edited_content") + '");\'>Save Edits</button>&nbsp;' +
        '<button type="button" class="hide btn btn-primary btn-small cancel_edits">Cancel Edits</button>' +
        '</div>' +
        '</div>' +
        '<div class="row-fluid">' +
        '<div class="date">' +
        '<p class="pull-right"><strong><span class="muted">Offered on: </span></strong>' + date[0] + '</p>' +
        '</div>');
    if (offers[i].Username == "<?php echo $_SESSION["
    username "]; ?>") {
        document.write('<div class="controls pull-right">' +
            '<a href="" class="no_link edit_offer">Edit</a>&nbsp;' +
            '<a href="" class="no_link" onclick="showDeleteOfferModal(' + offers[i].Offer_ID + ');">Delete</a> |&nbsp;' +
            '</div>');
    }
    document.write('</div>' +
        '</div>' +
        '</div>' +
        '<hr />');
}

The important part is:

...
'<div class="row-fluid">' +
    '<div class="content">' +
    '<p class="content">' + offers[i].Text + '</p>' +
    '<textarea class="hide span12" id="edited_content">' + offers[i].Text + '</textarea>' +
    '<button type="button" class="hide btn btn-primary btn-small" id="save_edits" onclick=\'editPostOffer("<?php echo $_GET["id"]; ?>","' + offers[i].Offer_ID + '","' + document.getElementById("edited_content") + '");\'>Save Edits</button>&nbsp;' +
    '<button type="button" class="hide btn btn-primary btn-small cancel_edits">Cancel Edits</button>' +
    '</div>' +
    '</div>' +
...

The most important is:

...
'<button type="button" class="hide btn btn-primary btn-small" id="save_edits" onclick=\'editPostOffer("<?php echo $_GET["id"]; ?>","' + offers[i].Offer_ID + '","' + document.getElementById("edited_content") + '");\'>Save Edits</button>&nbsp;' +
...

In the onclick of that button the function document.getElementById("edited_content") returns a null value. I've tried logging it to the console it prints null. Why is that happening?

Any help would be appreciated!

That is happening because when the string is interpreted (ie. before being inserted into the DOM) the `#edited_content` does not exist. — Rory McCrossan, Oct 11 '13 at 12:32
Also, it should be noted that using `document.write` to dump a massive string into the DOM is a terrible way of doing things. You should refactor this to create actual DOM nodes, or use a templating plugin. — Rory McCrossan, Oct 11 '13 at 12:34

score 1 · Accepted Answer · edited May 23 '17 at 11:57

Because at the point you call document.getElementById("edited_content"), edited_content does not exist.

You are creating it by appending a string, so you'd need to do something like:

// Add the first part
document.write('<div class="row-fluid offer">' +
        '<div class="span2">' +
        '<img class="profile_picture" src="' + offers[i].Picture_Path + '" />' +
        '</div>' +
        '<div class="span10">' +
        '<div class="row-fluid">' +
        '<div class="username">' +
        '<p style="font-weight: bold;">' + offers[i].Name + '</p>' +
        '</div>' +
        '</div>' +
        '<div class="row-fluid">' +
        '<div class="content">' +
        '<p class="content">' + offers[i].Text + '</p>' +
        '<textarea class="hide span12" id="edited_content">' + offers[i].Text + '</textarea>');
// Now we can get edited_content
document.write('<button type="button" class="hide btn btn-primary btn-small" id="save_edits" onclick=\'editPostOffer("<?php echo $_GET["id"]; ?>","' + offers[i].Offer_ID + '","' + document.getElementById("edited_content") + '");\'>Save Edits</button>&nbsp;');
// Write the rest of the HTML
document.write('<button type="button" class="hide btn btn-primary btn-small cancel_edits">Cancel Edits</button>' +
        '</div>' +
        '</div>' +
        '<div class="row-fluid">' +
        '<div class="date">' +
        '<p class="pull-right"><strong><span class="muted">Offered on: </span></strong>' + date[0] + '</p>' +
        '</div>');

P.S. You tagged the question with jQuery - there are much better ways of doing what you are trying to achieve. Better still, use a templating engine.

Well the code I provided should work. The links I provided should explain the better ways to solve this problem. The rest you'll have to do yourself — CodingIntrigue, Oct 11 '13 at 12:38

document.getElementById is returning null on the button click

1 Answers1