首先执行使用lodash，tap（）的链

Question

我正在尝试使用lodash链同步执行操作，但似乎首先执行.tap（），我无法找到使用promise这样做的正确方法。我虽然lodash中的链允许操作以同步方式跟随，但意味着点击将不会执行，直到forEach结束

const ids = [
      {
        "id": 1,
        "refs": [
          {
              "skuId": 693194,
              "sizeId": "12M",
              "colorId": "ROSE"
          },
          {
              "skuId": 693195,
              "sizeId": "14M",
              "colorId": "ROSE"
          },
          {
              "skuId": 973804,
              "sizeId": "6M",
              "colorId": "GREEN"
          }
        ]
       },
       {
        "id": 2,
        "refs": [
          {
              "skuId": 693174,
              "sizeId": "13M",
              "colorId": "RED"
          },
          {
              "skuId": 693995,
              "sizeId": "14M",
              "colorId": "BLUS"
          }
        ]
       } 
     ]
     
     let id = 1
     
     _(ids)
     .chain()
     .map(value => {
        id = _.result(_.find(value.refs, function(sku) {
                  return sku.colorId === 'ROSE' && 
                    sku.sizeId === '14M';
                                    }), 'skuId');
                                    
     })
     .tap(() => console.log('id: ', id))
     .value()

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

Answer 1

我认为您没有正确使用chain - check out the docs，您必须通过调用.value()来解包该值，就像在文档示例中一样。 Tap实际上并未先执行。

let id = null;

_.chain(ids)
  .forEach(value => {
    id = _.result(_.find(value.refs, function(sku) {
      return sku.colorId === 'ROSE'
        && sku.sizeId === '14M';
       }), 'skuId');                                      
  })
  .tap(() => console.log(id))
  .value();

我不是100％确定你要做什么，但我会重写它以使用map来摆脱那个外在的id：

const ids = [
  {
    "id": 1,
    "refs": [
      {
          "skuId": 693194,
          "sizeId": "12M",
          "colorId": "ROSE"
      },
      {
          "skuId": 693195,
          "sizeId": "14M",
          "colorId": "ROSE"
      },
      {
          "skuId": 973804,
          "sizeId": "6M",
          "colorId": "GREEN"
      }
    ]
   },
   {
    "id": 2,
    "refs": [
      {
          "skuId": 693174,
          "sizeId": "13M",
          "colorId": "RED"
      },
      {
          "skuId": 693995,
          "sizeId": "14M",
          "colorId": "BLUS"
      }
    ]
   } 
 ]

let val = _.chain(ids)
  .map(value => {
    return _.result(
      _.find(
        value.refs,
        sku => sku.colorId === 'ROSE' && sku.sizeId === '14M'
      ),
      'skuId');
  })
  .value();

console.log(val);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

您仍然可能需要稍微调整一下代码以获得您期望的结果。

Answer 2

如果您在id内添加一行以转储map的值，您会注意到id被设置了两次而第二次被null覆盖了你想要的价值。

const ids = [
      {
        "id": 1,
        "refs": [
          {
              "skuId": 693194,
              "sizeId": "12M",
              "colorId": "ROSE"
          },
          {
              "skuId": 693195,
              "sizeId": "14M",
              "colorId": "ROSE"
          },
          {
              "skuId": 973804,
              "sizeId": "6M",
              "colorId": "GREEN"
          }
        ]
       },
       {
        "id": 2,
        "refs": [
          {
              "skuId": 693174,
              "sizeId": "13M",
              "colorId": "RED"
          },
          {
              "skuId": 693995,
              "sizeId": "14M",
              "colorId": "BLUS"
          }
        ]
       } 
     ]
     
     let id = 1
     
     _(ids)
     .chain()
     .map(value => {
        id = _.result(_.find(value.refs, function(sku) {
                  return sku.colorId === 'ROSE' && 
                    sku.sizeId === '14M';
                                    }), 'skuId');
        // Add this line to inspect the id value in map
        console.log('id (in map): ', id);
     })
     .tap(() => console.log('id: ', id))
     .value()

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>