Trigger CSS3 transition on page load

Question

I am trying to achieve a loading effect on the page load by CSS3 width transition. Here is the demo.

HTML

        
                      

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Answer 1

By removing the class from the span and setting it in JavaScript the browser will apply the transition, but this only works on the first .skill-bar. Also .getElementsByClassName will not work in IE8 or below.

HTML

<div class="skill-bar"><span></span></div>

JavaScript

document.getElementsByClassName('skill-bar')[0].getElementsByTagName('span')[0].className = 'w70';

(so just wrap this in <script> element after the HTML or see run function when page is loaded

Pure JavaScript demo

You probably want a jQuery (or other framework) solution to ensure cross-browser compatibility but that introduces a dependency on the framework. If you include jQuery already then great. If not you will need to include that library first and then use:

jQuery

$(window).load(function(){
    $('.skill-bar span').addClass('w70');
});

jQuery demo

Right click on the output frame and select View frame source to see the output code.

Answer 2

Add the class throught javascript:

$(".skill-bar span").addClass("w70");

See fiddle here.

Answer 3

You can achieve the effect without JavaScript and without any compatibility issue using CSS animation:

<div class="skill-bar">
    <span class="w70"></span>
</div>

---

.skill-bar {
    width: 57%;
    float: left;
    height: 11px;
    border-radius: 5px;
    position: relative;
    margin: 6px 0 12px 0;
    border: 2px solid #00edc2;
}
.skill-bar span {
    background: #00edc2;
    height: 7px;
    border-radius: 5px;
    display: inline-block;
}
.skill-bar span {
    animation: w70 1s ease forwards;
}
.skill-bar .w70 {
    width: 70%;
}
@keyframes w70 {
    from { width: 0%; }
    to { width: 70%; }
}

Fiddle for webkit: http://jsfiddle.net/ySj7t/