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potato-load.js
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potato-load.js
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(function(window) {
var isElementInViewport= function(el) {
var rect = el.getBoundingClientRect();
return !(
rect.left > (window.innerWidth || document.documentElement.clientWidth) ||
rect.right < 0 ||
rect.top > (window.innerHeight || document.documentElement.clientHeight) ||
rect.bottom < 0
);
};
var check = function(el) {
if (isElementInViewport(el)) {
el.setAttribute('src', el.getAttribute('data-src'));
}
};
// copied from underscore
var debounce = function(func, wait, options) {
var context, args, result;
var timeout = null;
var previous = 0;
options || (options = {});
var later = function() {
previous = options.leading === false ? 0 : new Date;
timeout = null;
result = func.apply(context, args);
};
return function() {
var now = new Date;
if (!previous && options.leading === false) previous = now;
var remaining = wait - (now - previous);
context = this;
args = arguments;
if (remaining <= 0) {
clearTimeout(timeout);
timeout = null;
previous = now;
result = func.apply(context, args);
} else if (!timeout && options.trailing !== false) {
timeout = setTimeout(later, remaining);
}
return result;
};
};
window.potatoload = function(selector) {
// Get DOM objects
var elements = Array.prototype.slice.call(document.querySelectorAll(selector));
// Check on scroll and visible imgs on load
elements.forEach(function(el, idx) {
// debounce so we don't check intersections for every pixel scrolled
window.addEventListener('scroll', debounce(check.bind(this, el), 100));
check(el);
});
};
})(window);