#intersectionobserver code explainers

typescript

import { useEffect, useState } from "react";
 
interface Section {
  id: string;

Building a scroll-spy hook in React

custom-hooks intersectionobserver dom-observation

Intermediate 8 steps

typescript

import {
  Directive,
  ElementRef,
  EventEmitter,

An infinite-scroll directive in Angular

intersectionobserver directives performance

Advanced 7 steps

javascript

function initScrollSpy() {
  const links = Array.from(document.querySelectorAll('.nav a[href^="#"]'));
  const sections = links
    .map((link) => document.querySelector(link.getAttribute('href')))

Building a scroll spy with IntersectionObserver

intersectionobserver dom event-driven

Intermediate 7 steps

typescript

type LazyImageOptions = {
  rootMargin?: string;
  loadedClass?: string;
};

Lazy-loading images with IntersectionObserver

intersectionobserver lazy-loading performance

Intermediate 7 steps

javascript

class InfiniteScroll {
  constructor(sentinel, { loadMore, root = null, rootMargin = '200px' } = {}) {
    this.sentinel = sentinel;
    this.loadMore = loadMore;

Infinite scroll with IntersectionObserver

intersectionobserver pagination async

Intermediate 10 steps

javascript

function initLazyLoad(root = document) {
  const images = root.querySelectorAll('img[data-src]');
 
  if (!('IntersectionObserver' in window)) {

How lazy image loading works

lazy-loading intersectionobserver progressive-enhancement

Intermediate 8 steps