循环通过 object 并仅返回某些键及其值

Question

Given the following object, how can I loop through this object inorder to obtain both keys and values but only for the following keys:

    "myName": "Demo"
    "active": "Y"
    "myCode": "123456789"
    "myType": 1


let a = {
    "values": {
        "myName": "Demo",
        "active": "Y",
        "myCode": "123456789",
        "myType": 1,
        "myGroups": [
            {
                "myGroupName": "Group 1",
                "myTypes": [
                    {
                        "myTypeName": "323232",
                        "myTypeId": "1"
                    }
                ]
            },
            {
                "myGroupName": "Group 2",
                "myTypes": [
                    {
                        "myTypeName": "523232",
                        "myTypeId": "2"
                    }
                ]
            }
        ]
    }
}

I have tried:

for (const [key, value] of Object.entries(a.values)) {
  console.log(`${key}: ${value}`);
For}

but this will return all keys with their values.

Answer 1

You can use a dictionary (array) to contain the keys you want to extract the properties for, and then reduce over the values with Object.entries to produce a new object matching only those entries included in the dictionary.

 let a = { "values": { "myName": "Demo", "active": "Y", "myCode": "123456789", "myType": 1, "myGroups": [{ "myGroupName": "Group 1", "myTypes": [{ "myTypeName": "323232", "myTypeId": "1" }] }, { "myGroupName": "Group 2", "myTypes": [{ "myTypeName": "523232", "myTypeId": "2" }] } ] } } const arr = [ 'myName', 'active', 'myCode', 'myType' ]; const out = Object.entries(a.values).reduce((acc, [key, value]) => { if (arr.includes(key)) acc[key] = value; return acc; }, {}); console.log(out);

Answer 2

The best answer would be to set up an array of the desired keys and then iterate over that array instead of an array of the original object's entries. This is how you would achieve that:

 let a = { values: { myName: "Demo", active: "Y", myCode: "123456789", myType: 1, myGroups: [{ myGroupName: "Group 1", myTypes: [{ myTypeName: "323232", myTypeId: "1" }] }, { myGroupName: "Group 2", myTypes: [{ myTypeName: "523232", myTypeId: "2" }] }] } }; const keys = ['myName', 'active', 'myCode', 'myType']; const cherryPick = (obj, keys) => keys.reduce((a,c) => (a[c] = obj[c], a), {}); console.log(cherryPick(a.values, keys));

The above example will work for many provided keys. If a key does not exist in the supplied object, its value will be undefined. If you want to only keep properties which have values, simply add an optional filter to the cherryPick() function, like this:

 let test = { a: 1, b: 2 }; const keys = ['a', 'b', 'c']; const cherryPick = (obj, keys, filter = 0) => keys.filter(key => filter? obj[key]: 1).reduce((acc,key) => (acc[key] = obj[key], acc), {}); console.log('STORE undefined:: cherryPick(test, keys)', cherryPick(test, keys)); console.log('FILTER undefined:: cherryPick(test, keys, 1)', cherryPick(test, keys, true));

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