JavaScript controls the method to call the callback function after the image is loaded

This article illustrates how JavaScript calls the callback function after the image is loaded. Share with you for your reference. The specific analysis is as follows:

This code controls the execution of the specified callback function after the image in the specified area is loaded.

function when_images_loaded($img_container, callback) {

/* do callback when images in $img_container (jQuery object) are loaded. Only works when ALL images in $img_container are newly inserted images and this function is called immediately after images are inserted into the target. */

    var _imgs = $img_container.find('img'),

        img_length = _imgs.length,

        img_load_cntr = 0;

    if (img_length) {//if the $img_container contains new images.

        _imgs.on('load', function() {//then we avoid the callback until images are loaded

            img_load_cntr++;

            if (img_load_cntr == img_length) {

                callback();

            }

        });

    }

    else { //otherwise just do the main callback action if there's no images in $img_container.

        callback();

    }

}

I hope this article is helpful for you to design javascript program.