carbon-components/src/globals/js/mixins/track-blur.js

Carbon Components is a component library for IBM Cloud

import on from '../misc/on';
import handles from './handles';

function trackBlur(ToMix) {
  class TrackBlur extends ToMix {
    /**
     * Mix-in class to add an handler for losing focus.
     * @extends Handles
     * @param {HTMLElement} element The element working as this component.
     * @param {Object} [options] The component options.
     */
    constructor(element, options) {
      super(element, options);
      const hasFocusin = 'onfocusin' in window;
      const focusinEventName = hasFocusin ? 'focusin' : 'focus';
      this.manage(
        on(
          this.element.ownerDocument,
          focusinEventName,
          event => {
            if (!this.element.contains(event.target)) {
              this.handleBlur(event);
            }
          },
          !hasFocusin
        )
      );
    }

    /**
     * The method called when this component loses focus.
     * @abstract
     */
    handleBlur() {
      throw new Error('Components inheriting TrackBlur mix-in must implement handleBlur() method.');
    }
  }

  return TrackBlur;
}

const exports = [handles, trackBlur];
export default exports;