carbon-components/es/globals/js/misc/on-focus-by-keyboard.js

Carbon Components is a component library for IBM Cloud

/**
 * Differentiate between keyboard and mouse-triggered focusout/blur events
 * @param {Element} node  The element to attach event listeners to
 * @param {string} name The event name to listen to
 * @param {Function} callback The callback function to invoke
 * @returns {Handle} The handle to release the attached event handler
 */
export default function onFocusByKeyboard(node, name, callback) {
  var hasFocusout = 'onfocusout' in window;
  var focusinEventName = hasFocusout ? 'focusin' : 'focus';
  var focusoutEventName = hasFocusout ? 'focusout' : 'blur';
  /**
   * Event types supported by this function
   * @type {Object<string, string>}
   */

  var supportedEvents = {
    focus: focusinEventName,
    blur: focusoutEventName
  };
  var eventName = supportedEvents[name];

  if (!eventName) {
    throw new Error('Unsupported event!');
  }

  var clicked;

  var handleMousedown = function handleMousedown() {
    clicked = true;
    requestAnimationFrame(function () {
      clicked = false;
    });
  };

  var handleFocusin = function handleFocusin(evt) {
    if (!clicked) {
      callback(evt);
    }
  };

  node.ownerDocument.addEventListener('mousedown', handleMousedown);
  node.addEventListener(eventName, handleFocusin, !hasFocusout);
  return {
    release: function release() {
      if (handleFocusin) {
        node.removeEventListener(eventName, handleFocusin, !hasFocusout);
        handleFocusin = null;
      }

      if (handleMousedown) {
        node.ownerDocument.removeEventListener('mousedown', handleMousedown);
        handleMousedown = null;
      }

      return null;
    }
  };
}