ProperJS // ImageLoader

Bullet-proof lazy-loading images with contextual load conditions.

Installation

npm i properjs-imageloader --save-dev

Usage

Given a set of elements on the page such as this. Also see the test setup which loads over 40 images from kitajchuk.com.

<img class="image" data-src="https://www.kitajchuk.com/assets/img/kickflip/kickflip_01.png" />
<img class="image" data-src="https://www.kitajchuk.com/assets/img/kickflip/kickflip_02.png" />
<img class="image" data-src="https://www.kitajchuk.com/assets/img/kickflip/kickflip_03.png" />

You can pool them into a manager for loading in this manner. The executor is what determines the criteria for an image in the pool actually loading, the default is to be within the viewport. The built-in executor uses getBoundingClientRect() to check an image or element's position within the viewport.

import ImageLoader from "../ImageLoader";
 
const loader = new ImageLoader({
    elements: document.querySelectorAll( ".image" ),
    property: "data-src", // default
    executor: ( el ) => { // default
        const bounds = el.getBoundingClientRect();
 
        return (bounds.top < window.innerHeight && bounds.bottom > 0);
    },
    loadType: "async", // default
});
 
loader.on( "load", ( el ) => {
    console.log( "loaded", el.src );
 
}).on( "error", ( el ) => {
    console.log( "error", el.src );
 
}).on( "done", () => {
    console.log( "done" );
});