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Observe

JavaScript

observe.js Raw #

const callback = (entries) => {
  entries.forEach((entry) => {
    if (entry.isIntersecting) {
      // `entry.target` 是 dom 元素
      console.log(`${entry.target.id} is visible`);
    }
  });
};
const options = {
  threshold: 1.0,
};
const observer = new IntersectionObserver(callback, options);
const btn = document.getElementById( btn );
const bottomBtn = document.getElementById( bottom-btn );
observer.observe(btn);
observer.observe(bottomBtn);