Method addElStyles

src/utils.ts:667–682

(el: HTMLElement, styles: { [prop: string]: string | string[] })

  // }

  public static addElStyles(el: HTMLElement, styles: { [prop: string]: string | string[] }): void {
    if (styles instanceof Object) {
      for (const s in styles) {
        if (styles.hasOwnProperty(s)) {
          if (Array.isArray(styles[s])) {
            // support fallback value
            (styles[s] as string[]).forEach(val => {
              el.style[s] = val;
            });
          } else {
            el.style[s] = styles[s];
          }
        }
      }
    }
  }

  public static initEvent<T>(e: DragEvent | MouseEvent, info: { type: string; target?: EventTarget }): T {
    const evt = { type: info.type };