JSON.stringify 替换 属性

function replacer(key, value) {
  if (typeof value === "string") {
    return undefined;
  }
  return value;
}

var foo = {foundation: "Mozilla", model: "box", week: 45, transport: "car", month: 7};
var jsonString = JSON.stringify(foo, replacer);

JSON 序列化结果为 {"week":45,"month":7}.


如果是一个数组： 
JSON.stringify(foo, ['week', 'month']);
// '{"week":45,"month":7}', 只保留 “week” 和 “month” 属性值。