+/**
+ * Animate the css styles of an element using FLIP animation techniques.
+ * Styles must be an object where the keys are style properties, camelcase, and the values
+ * are an array of two items in the format [initialValue, finalValue]
+ * @param {Element} element
+ * @param {Object} styles
+ * @param {Number} animTime
+ * @param {Function} onComplete
+ */
+function animateStyles(element, styles, animTime = 400, onComplete = null) {
+ const styleNames = Object.keys(styles);
+ for (const style of styleNames) {
+ element.style[style] = styles[style][0];
+ }
+
+ const cleanup = () => {
+ for (const style of styleNames) {
+ element.style[style] = null;
+ }
+ element.style.transition = null;
+ element.removeEventListener('transitionend', cleanup);
+ animateStylesCleanupMap.delete(element);
+ if (onComplete) onComplete();
+ };
+
+ setTimeout(() => {
+ element.style.transition = `all ease-in-out ${animTime}ms`;
+ for (const style of styleNames) {
+ element.style[style] = styles[style][1];
+ }
+
+ element.addEventListener('transitionend', cleanup);
+ animateStylesCleanupMap.set(element, cleanup);
+ }, 15);
+}
+
+/**
+ * Run the active cleanup action for the given element.
+ * @param {Element} element
+ */
+function cleanupExistingElementAnimation(element) {
+ if (animateStylesCleanupMap.has(element)) {
+ const oldCleanup = animateStylesCleanupMap.get(element);
+ oldCleanup();
+ }
+}
+
+/**
+ * Fade in the given element.
+ * @param {Element} element
+ * @param {Number} animTime
+ * @param {Function|null} onComplete
+ */
+export function fadeIn(element, animTime = 400, onComplete = null) {
+ cleanupExistingElementAnimation(element);
+ element.style.display = 'block';
+ animateStyles(element, {
+ opacity: ['0', '1'],
+ }, animTime, () => {
+ if (onComplete) onComplete();
+ });
+}
+