如果匹配条件，则在对象数组中添加键

Question

我正在尝试根据条件获取一组对象。如果该值为真，则仅将该键和值添加到新的对象数组中。但是，它给出了错误：  const arr = [{id: 123, val: 'abcd', other: 'abcd'}, {id: 123, val: 'abcd', other: 'abcd', show: true}, {id: 123, val: 'abcd', other: 'abcd', show: false}, {id: 123, val: 'abcd', other: 'abcd'}]const newArr = arr.map(item => ({id: item.id, val: item.val != null ? item.val : ''}))console.log(newArr); //It is workingconst arr = [{id: 123, val: 'abcd', other: 'abcd'}, {id: 123, val: 'abcd', other: 'abcd', show: true}, {id: 123, val: 'abcd', other: 'abcd', show: false}, {id: 123, val: 'abcd', other: 'abcd'}]const expectedArr = arr.map(item => ({id: item.id, val: item.val != null ? item.val : '', (item.show) && (show: item.show)}))console.log(expectedArr); //Shows error预期结果：[  {    "id": 123,    "val": "abcd"  },  {    "id": 123,    "val": "abcd"    "show": true  },  {    "id": 123,    "val": "abcd"  },  {    "id": 123,    "val": "abcd"  }]任何帮助将不胜感激。

Answer 1

那 ？

const arr = 

      [ { id: 123, val: 'abcd', other: 'abcd' } 

      , { id: 123, val: 'abcd', other: 'abcd', show: true  } 

      , { id: 123, val: 'abcd', other: 'abcd', show: false } 

      , { id: 123, val: 'abcd', other: 'abcd' } 

      ] 

const newArr = arr.map(({id,val,show})=>show?{id,val,show}:{id,val})

console.log( newArr )

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Answer 2

你可以像这样重写它。使用这种语法，当item.show括号为真时，您将解析为和对象，然后您只需将其传播到您的对象中。您还可以使用无效合并来分配item.val

 const expectedArr = arr.map((item) => ({

      id: item.id,

      val: item.val ?? "",

      ...(item.show && { show: item.show }),

    }));

Answer 3

目前，它在函数内部的一行中包含多个条件，Array.map并且无效。

const arr = [{id: 123, val: 'abcd', other: 'abcd'}, {id: 123, val: 'abcd', other: 'abcd', show: true}, {id: 123, val: 'abcd', other: 'abcd', show: false}, {id: 123, val: 'abcd', other: 'abcd'}]

const result = arr.map(({ id, val, show }) => {

  const newObj = {

    id,

    val: val != null ? val : ''

  };

  if (show) {

    newObj['show'] = show;

  }

  return newObj;

});

console.log(result);

Answer 4

const arr = [{id: 123, val: 'abcd', other: 'abcd'}, {id: 123, val: 'abcd', other: 'abcd', show: true}, {id: 123, val: 'abcd', other: 'abcd', show: false}, {id: 123, val: 'abcd', other: 'abcd'}]

const expectedArr = arr.map(item => ({id: item.id, val: item.val? item.val: '', show: item.show? item.show: 0}))

console.log(expectedArr); //solved-ish

//but honestly, that's the furthest i can go with your strange code golfed syntax setup.. to be honest, using ? is similar to if but NOT if, it's closer to || but anyway

console.log('skip what was above, the moment of truth below')

const theRealAnswer = arr.map(item=>{ const i={id: item.id, val: item.val? item.val: '', show: item.show? item.show: 0};if(!i.show){delete(i.show)}return(i) })

console.log(theRealAnswer)

//now, the logical construct(what u gave the mapper) was impossible to do what u wanted. coding isn't just syntax, it's logic too. you cannot assign a key to completely delete the key itself