javascript - Node : Find object from array not contained in another array

Question

我有两个对象数组:

var existingUsers1 = [];
    existingUsers1.push({
        "userName": "A",
        "departmentId": "1"
    });
    existingUsers1.push({
        "userName": "B",
        "departmentId": "1"
    });
    existingUsers1.push({
        "userName": "C",
        "departmentId": "1"
    });
    existingUsers1.push({
        "userName": "D",
        "departmentId": "1"
    });

var existingUsers2 = [];
    existingUsers2.push({
        "userName": "A",
        "departmentId": "1"
    });
    existingUsers2.push({
        "userName": "B",
        "departmentId": "1"
    });

我需要从 existingUsers1 中找到 existingUsers2 中不存在的对象。我可以使用 nodeJS 中的任何函数来实现此目的或任何其他方式吗？

Answer 1

你可以使用 Set与 Array#filter .

var existingUsers1 = [{ userName: "A", departmentId: "1" }, { userName: "B", departmentId: "1" }, { userName: "C", departmentId: "1" }, { userName: "D", departmentId: "1" }],
    existingUsers2 = [{ userName: "A", departmentId: "1" }, { userName: "B", departmentId: "1" }],
    hash = new Set(existingUsers2.map(o => o.userName)),
    result = existingUsers1.filter(o => !hash.has(o.userName));

console.log(result);

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