Vim-Vixen/src/content/components/common/hint.js

import './hint.css';

export default class Hint {
  constructor(target, tag) {
    if (!(document.body instanceof HTMLElement)) {
      throw new TypeError('target is not an HTMLElement');
    }

    this.target = target;

    let doc = target.ownerDocument;
    let { top, left } = target.getBoundingClientRect();
    let { scrollX, scrollY } = window;

    this.element = doc.createElement('span');
    this.element.className = 'vimvixen-hint';
    this.element.textContent = tag;
    this.element.style.left = left + scrollX + 'px';
    this.element.style.top = top + scrollY + 'px';

    this.show();
    doc.body.append(this.element);
  }

  show() {
    this.element.style.display = 'inline';
  }

  hide() {
    this.element.style.display = 'none';
  }

  remove() {
    this.element.remove();
  }
}