Javascript中对象数组的比较与获取

Question

这个变量数据能与输出匹配吗？我试着组合它，但它不起作用，它只产生了1行，这与结果不匹配。我尝试过使用排序，但我仍然不知道如何显示数组的两个侧面-就像那样。

//Output Associative-Array
[
["row3", "row5"],

["row1", "row2"],

["row4", ""],

["", "row6"],

["row7", "row8"]
]

这是我的代码

   const arr = [
    {id: 2, value: 'row1', position: 'S'},
    {id: 2, value: 'row2', position: 'A'},
    {id: 1, value: 'row3', position: 'S'},
    {id: 3, value: 'row4', position: 'S'},
    {id: 1, value: 'row5', position: 'A'},
    {id: 4, value: 'row6', position: 'A'},
    {id: 5, value: 'row7', position: 'S'},
    {id: 5, value: 'row8', position: 'A'}
  ]

Answer 1

您可以使用数组reduce方法执行以下操作：

​

arr = [
    {id: 2, value: 'row1', position: 'S'},
    {id: 2, value: 'row2', position: 'A'},
    {id: 1, value: 'row3', position: 'S'},
    {id: 3, value: 'row4', position: 'S'},
    {id: 1, value: 'row5', position: 'A'},
    {id: 4, value: 'row6', position: 'A'},
    {id: 5, value: 'row7', position: 'S'},
    {id: 5, value: 'row8', position: 'A'}
  ]

arr.sort((a,b) => a.id - b.id);

ret = arr.reduce((prev, curr) => {
  if(!prev[curr.id - 1]) {
    prev[curr.id - 1] = ['', ''];
    
  }
  
  if(curr.position === 'A') {
      prev[curr.id - 1][1] = curr.value;
    } else {
      prev[curr.id - 1][0] = curr.value;
    }
 
  return prev;
}, {});

console.log(Object.values(ret));

​