Set data attribute using JavaScript

Question

I am using The DynaTree (https://code.google.com/p/dynatree) but I am having some problems and hoping someone can help..

I am displaying the tree on the page like below:

<div id="tree">
        <ul>
            <li class="folder">Outputs
                <ul>
                    <li id="item1" data="icon: 'base.gif', url: 'page1.htm', target: 'AccessPage'">Item 1 Title
                    <li id="item2" data="icon: 'base.gif', url: 'page2.htm', target: 'AccessPage'">Item 2 Title
                    <li id="item3" data="icon: 'base.gif', url: 'page3.htm', target: 'AccessPage'">Item 3 Title
                    <li id="item4" data="icon: 'base.gif', url: 'page4.htm', target: 'AccessPage'">Item 4 Title
                </ul>
        </ul>
    </div>

However I am trying to change the icon on a item no matter if it's selected or not only using JavaScript.

the new icon I want to use is base2.gif

I have tried using the following but it don't seem to work:

document.getElementById('item1').data = "icon: 'base2.gif', url: 'output.htm', target: 'AccessPage', output: '1'";

anyone know what I might be doing wrong?

Answer 1

Use the setAttribute method:

document.getElementById('item1').setAttribute('data', "icon: 'base2.gif', url: 'output.htm', target: 'AccessPage', output: '1'");

But you really should be using data followed with a dash and with its property, like:

<li ... data-icon="base.gif" ...>

And to do it in JS use the dataset property:

document.getElementById('item1').dataset.icon = "base.gif";

Answer 2

Please use dataset

var article = document.querySelector('#electriccars'),
    data = article.dataset;

// data.columns -> "3"
// data.indexnumber -> "12314"
// data.parent -> "cars"

so in your case for setting data:

getElementById('item1').dataset.icon = "base2.gif";