bootstrap-modal-form/src/js/bootstrap/mdb-prefix/util/scrollbar.js

Bootstrap modal forms are displayed-on-action pop-up forms that are used for gathering data from website visitors, to register or log users.

/**
 * --------------------------------------------------------------------------
 * Bootstrap (v5.1.3): util/scrollBar.js
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
 * --------------------------------------------------------------------------
 */

import SelectorEngine from '../dom/selector-engine';
import Manipulator from '../dom/manipulator';
import { isElement } from './index';

const SELECTOR_FIXED_CONTENT = '.fixed-top, .fixed-bottom, .is-fixed, .sticky-top';
const SELECTOR_STICKY_CONTENT = '.sticky-top';

class ScrollBarHelper {
  constructor() {
    this._element = document.body;
  }

  getWidth() {
    // https://developer.mozilla.org/en-US/docs/Web/API/Window/innerWidth#usage_notes
    const documentWidth = document.documentElement.clientWidth;
    return Math.abs(window.innerWidth - documentWidth);
  }

  hide() {
    const width = this.getWidth();
    this._disableOverFlow();
    // give padding to element to balance the hidden scrollbar width
    this._setElementAttributes(
      this._element,
      'paddingRight',
      (calculatedValue) => calculatedValue + width
    );
    // trick: We adjust positive paddingRight and negative marginRight to sticky-top elements to keep showing fullwidth
    this._setElementAttributes(
      SELECTOR_FIXED_CONTENT,
      'paddingRight',
      (calculatedValue) => calculatedValue + width
    );
    this._setElementAttributes(
      SELECTOR_STICKY_CONTENT,
      'marginRight',
      (calculatedValue) => calculatedValue - width
    );
  }

  _disableOverFlow() {
    this._saveInitialAttribute(this._element, 'overflow');
    this._element.style.overflow = 'hidden';
  }

  _setElementAttributes(selector, styleProp, callback) {
    const scrollbarWidth = this.getWidth();
    const manipulationCallBack = (element) => {
      if (element !== this._element && window.innerWidth > element.clientWidth + scrollbarWidth) {
        return;
      }

      this._saveInitialAttribute(element, styleProp);
      const calculatedValue = window.getComputedStyle(element)[styleProp];
      element.style[styleProp] = `${callback(Number.parseFloat(calculatedValue))}px`;
    };

    this._applyManipulationCallback(selector, manipulationCallBack);
  }

  reset() {
    this._resetElementAttributes(this._element, 'overflow');
    this._resetElementAttributes(this._element, 'paddingRight');
    this._resetElementAttributes(SELECTOR_FIXED_CONTENT, 'paddingRight');
    this._resetElementAttributes(SELECTOR_STICKY_CONTENT, 'marginRight');
  }

  _saveInitialAttribute(element, styleProp) {
    const actualValue = element.style[styleProp];
    if (actualValue) {
      Manipulator.setDataAttribute(element, styleProp, actualValue);
    }
  }

  _resetElementAttributes(selector, styleProp) {
    const manipulationCallBack = (element) => {
      const value = Manipulator.getDataAttribute(element, styleProp);
      if (typeof value === 'undefined') {
        element.style.removeProperty(styleProp);
      } else {
        Manipulator.removeDataAttribute(element, styleProp);
        element.style[styleProp] = value;
      }
    };

    this._applyManipulationCallback(selector, manipulationCallBack);
  }

  _applyManipulationCallback(selector, callBack) {
    if (isElement(selector)) {
      callBack(selector);
    } else {
      SelectorEngine.find(selector, this._element).forEach(callBack);
    }
  }

  isOverflowing() {
    return this.getWidth() > 0;
  }
}

export default ScrollBarHelper;