检查数组长度 object javascript

Question

I have some object like this

    const array = 
    {
      "entities": [
        {
          "annexes": [
            {
              "buildingUniqueIds": []
            },
            {
              "buildingUniqueIds": []
            },
            {
              "buildingUniqueIds": []
            },
          ],
          "buildingUniqueIds": []
        }
      ]
}

I need to check if any of those array is empty to return true, is this possible to do in one iteration, here is what I have tried for now, but some does not check array length it always return true even if array is empty:(

  get haveBuildingUniqueIds(): boolean {
    const condition1 = this.array.entities.some(x => x.annexes.some(y => y.buildingUniqueIds.some));
    const condition2 = this.array.entities.some(x => x.buildingUniqueIds.some);
    return condition1 && condition2;
  }

Answer 1

some is the right method to use, but it's a method , not a flag, so your innermost .some(y => y.buildingUniqueIds.some) will always return true , because a method is a truthy value.

Instead, check length :

const hasEmpties = array.entities.some(({annexes, buildingUniqueIds}) =>
    buildingUniqueIds.length === 0 ||
    annexes.some(({buildingUniqueIds}) => buildingUniqueIds.length === 0)
);

Live Example:

 function check(label, array) { const hasEmpties = array.entities.some(({annexes, buildingUniqueIds}) => buildingUniqueIds.length === 0 || annexes.some(({buildingUniqueIds}) => buildingUniqueIds.length === 0) ); console.log(label, "=>", hasEmpties); } check("all empty", { "entities": [ { "annexes": [ { "buildingUniqueIds": [] }, { "buildingUniqueIds": [] }, { "buildingUniqueIds": [] }, ], "buildingUniqueIds": [] } ] }); check("none empty", { "entities": [ { "annexes": [ { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [{}] }, ], "buildingUniqueIds": [{}] } ] }); check("entities.buildingUniqueIds empty", { "entities": [ { "annexes": [ { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [{}] }, ], "buildingUniqueIds": [] } ] }); check("entities.annexes.buildingUniqueIds[1] empty", { "entities": [ { "annexes": [ { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [] }, { "buildingUniqueIds": [{}] }, ], "buildingUniqueIds": [{}] } ] });

Side note: If you like, you can use .buildingUniqueIds.length rather than buildingUniqueIds.length === 0 .

Or without destructuring if you prefer:

const hasEmpties = array.entities.some(entity =>
    entity.buildingUniqueIds.length === 0 ||
    entity.annexes.some(annex => annex.buildingUniqueIds.length === 0)
);

Live Example:

 function check(label, array) { const hasEmpties = array.entities.some(entity => entity.buildingUniqueIds.length === 0 || entity.annexes.some(annex => annex.buildingUniqueIds.length === 0) ); console.log(label, "=>", hasEmpties); } check("all empty", { "entities": [ { "annexes": [ { "buildingUniqueIds": [] }, { "buildingUniqueIds": [] }, { "buildingUniqueIds": [] }, ], "buildingUniqueIds": [] } ] }); check("none empty", { "entities": [ { "annexes": [ { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [{}] }, ], "buildingUniqueIds": [{}] } ] }); check("entities.buildingUniqueIds empty", { "entities": [ { "annexes": [ { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [{}] }, ], "buildingUniqueIds": [] } ] }); check("entities.annexes.buildingUniqueIds[1] empty", { "entities": [ { "annexes": [ { "buildingUniqueIds": [{}] }, { "buildingUniqueIds": [] }, { "buildingUniqueIds": [{}] }, ], "buildingUniqueIds": [{}] } ] });