class ResizeObserver {constructor(callback) {this.observables = [];// Array of observed elements that looks like this:// [{//   el: domNode,//   size: {height: x, width: y}// }]this.boundCheck = this.check.bind(this);this.boundCheck();this.callback = callback;}observe(el) {if (this.observables.some((observable) => observable.el === el)) {return;}const newObservable = {el: el,size: {height: el.clientHeight,width: el.clientWidth}}this.observables.push(newObservable);}unobserve(el) {this.observables = this.observables.filter((obj) => obj.el !== el);}disconnect() {this.observables = [];}check() {const changedEntries = this.observables.filter((obj) => {const currentHeight = obj.el.clientHeight;const currentWidth = obj.el.clientWidth;if (obj.size.height !== currentHeight || obj.size.width !== currentWidth) {obj.size.height = currentHeight;obj.size.width = currentWidth;return true;}}).map((obj) => obj.el);if (changedEntries.length > 0) {this.callback(changedEntries);}window.requestAnimationFrame(this.boundCheck);}}