查找嵌套数组的 object 子项的长度

Question

I have a JavaScript object. Is there a built-in or accepted best practice way to get the length of all the children, here in this case for the first object in array it should be one and for the second object two, and the total comes down to 3.

const testData = [
    {
        account: "A",
        children: [
            {
                account: "Test",
                children: [],
            },
        ],
    }, {
        account: "B",
        children: [
            {
                account: "Test1",
                children: [],
            },
            {
                account: "Test2",
                children: [],
            },
        ],
    },

]

Answer 1

The recursive solution, should you need it

 const testData = [ { account: "A", children: [ { account: "Test", children: [{account:"Test-Grandchild", children:[{account:"Test-Great-Grandchild", children:[]}]}], }, ], }, { account: "B", children: [ { account: "Test1", children: [], }, { account: "Test2", children: [], }, ], }, ] const countChildren = obj => obj.children.length + obj.children.reduce((acc,c) => acc + countChildren(c), 0 ); const result = testData.reduce ( (acc,c) => acc + countChildren(c),0) console.log(result);

Answer 2

Sure, Array.reduce

 const nOfTestDataChildren = [ { account: "A", children: [ { account: "Test", children: [], }, ], }, { account: "B", children: [ { account: "Test1", children: [], }, { account: "Test2", children: [], }, ], }, ].reduce( (acc, val) => acc + val.children.length, 0); console.log(nOfTestDataChildren);

Answer 3

I think Kooilnic 's answer perfect for the situation since we are reducing the array into a single number value and it should be accepted as the actual answer. But I want to propose another solution using Array.forEach :

 const testData = [ { account: "A", children: [ { account: "Test", children: [], }, ], }, { account: "B", children: [ { account: "Test1", children: [], }, { account: "Test2", children: [], }, ], }, ] let numberOfChildren = 0 testData.forEach(datum => numberOfChildren += datum.children.length) console.log({ numberOfChildren })