en.javascript.info/1-js/4-data-structures/5-object-for-in/4-multiply-numeric/solution.md

//+ run
var menu = {
  width: 200,
  height: 300,
  title: "My menu"
};

function isNumeric(n) { 
  return !isNaN(parseFloat(n)) && isFinite(n);
}

function multiplyNumeric(obj) {
  for(var key in obj) {
    if (isNumeric( obj[key] )) {
      obj[key] *= 2;
    }
  }
}

multiplyNumeric(menu);

alert("menu width="+menu.width+" height="+menu.height+" title="+menu.title);