contentWidth(w) {
    var content = this.content || this.document.body;

    if (w && Object(_utils_core__WEBPACK_IMPORTED_MODULE_1__["isNumber"])(w)) {
      w = w + "px";
    }

    if (w) {
      content.style.width = w;
    }

    return parseInt(this.window.getComputedStyle(content)["width"]);
  }
Get or Set width of the contents
@param {number} [w]
@returns {number} width