JavaScript

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JavaScript Events

From WikiOD

Page, DOM and Browser loading[edit | edit source]

This is an example to explain the variations of load events.

  1. onload event
<body onload="someFunction()">
<img src="image1" />
<img src="image2" />
</body>

<script>
    function someFunction() {
    console.log("Hi! I am loaded");
}
</script>

In this case, the message is logged once all the contents of the page including the images and stylesheets(if any) are completely loaded.

DOMContentLoaded event

document.addEventListener("DOMContentLoaded", function(event) {
    console.log("Hello! I am loaded");
});

In the above code, the message is logged only after the DOM/document is loaded (ie:once the DOM is constructed).

Self*invoking anonymous function

(function(){
    console.log("Hi I am an anonymous function! I am loaded");
})();

Here, the message gets logged as soon as the browser interprets the anonymous function. It means, this function can get executed even before the DOM is loaded.

Credit:Stack_Overflow_Documentation