_init(options) {

      // Setting defaults
      this.options = Object.assign(this.defaults, options);

      if (this.options.backgroundColor) {
        // This is being deprecated in favor of using the style HTML DOM property
        console.warn('DEPRECATION NOTICE: "backgroundColor" is being deprecated. Please use the "style.background" property.');
      }

      this.toastElement = null;

      this.options.gravity = options.gravity === "bottom" ? "toastify-bottom" : "toastify-top"; // toast position - top or bottom
      this.options.stopOnFocus = options.stopOnFocus === undefined ? true : options.stopOnFocus; // stop timeout on focus
      if(options.backgroundColor) {
        this.options.style.background = options.backgroundColor;
      }
    }
Init the Toastify class
@param {ToastifyConfigurationObject} options - The configuration object to configure Toastify
@param {string} [options.text=Hi there!] - Message to be displayed in the toast
@param {Element} [options.node] - Provide a node to be mounted inside the toast. node takes higher precedence over text
@param {number} [options.duration=3000] - Duration for which the toast should be displayed. -1 for permanent toast
@param {string} [options.selector] - CSS Selector on which the toast should be added
@param {url} [options.destination] - URL to which the browser should be navigated on click of the toast
@param {boolean} [options.newWindow=false] - Decides whether the destination should be opened in a new window or not
@param {boolean} [options.close=false] - To show the close icon or not
@param {string} [options.gravity=toastify-top] - To show the toast from top or bottom
@param {string} [options.position=right] - To show the toast on left or right
@param {string} [options.backgroundColor] - Sets the background color of the toast (To be deprecated)
@param {url} [options.avatar] - Image/icon to be shown before text
@param {string} [options.className] - Ability to provide custom class name for further customization
@param {boolean} [options.stopOnFocus] - To stop timer when hovered over the toast (Only if duration is set)
@param {Function} [options.callback] - Invoked when the toast is dismissed
@param {Function} [options.onClick] - Invoked when the toast is clicked
@param {Object} [options.offset] - Ability to add some offset to axis
@param {boolean} [options.escapeMarkup=true] - Toggle the default behavior of escaping HTML markup
@param {string} [options.ariaLive] - Announce the toast to screen readers
@param {Object} [options.style] - Use the HTML DOM style property to add styles to toast
@private