在析构时处理嵌套对象上缺少的属性

Question

我需要解构嵌套对象。当某些嵌套属性丢失时，在分配确实存在的属性时避免异常的最佳方法是什么？

const data = {
  title: 'hello',
  // nest: {
  //   road: 5
  // }
};

const { title, nest: { road = '' } } = data;

console.log(road);
/** i want it to return '' or undefined. 
 *  actually it returns: Cannot match against 'undefined' or 'null'
 * 
*/
console.log(title)
/** i want it to return 'hello'
 * actually: never got there as there was an exception.
 */

Answer 1

即使它具有进一步嵌套的对象销毁，您也可以在父对象级别分配给空对象（或带值）：

const { title, nest: { road = '<default road>' } = {} } = data;

const data = {
  title: 'hello',
   //nest: {
   //  road: 5
   //}
};

const { title, nest: { road = '<default road>' } = {} } = data;

console.log(title);
console.log(road);

而且，你做错了，如果你正在破坏使用

{title: englishTitle} = {title: 1234}

然后，您应该使用englishTitle来获取 value 1234，而不是title，或者使用

{title} = {title: 1234}

并使用title得到1234