从多维 object 中获取值到列表

Question

I have object:

data = {
    "usa": {
        "a": {
            "min": 1,
            "max": 2,
            "avg": 1.5
        },
        "b": {
            "min": 3,
            "max": 5,
            "avg": 4
        }
    },
    "canada": {
        "c": {
            "min": 1,
            "max": 2,
            "avg": 1.5
        }
    }
}

I would like receive all max values from second dimension, for example:

function getMaxValues(country: string): number[] {
    const maxValues: number[] = data[country]???

    return maxValues;
}

I any better way than iterate over this object and collect results? In other languages are special functions for this. I don't want use iteration because this object is very large and usually specific functions for this are more efficient.

Answer 1

You can do:

Object.values(data).flatMap((country) => {
   return Object.values(country).map(({max}) => max);
});

Answer 2

You need to get the country object values then map to get max value.

 let data = { "usa": { "a": { "min": 1, "max": 2, "avg": 1.5 }, "b": { "min": 3, "max": 5, "avg": 4 } }, "canada": { "c": { "min": 1, "max": 2, "avg": 1.5 } } } function getMaxValues(country) { const maxValues = Object.values(data[country]).map(v => v.max); return maxValues; } console.log(getMaxValues('usa'));

Answer 3

You can reduce the entries of the object:

 const data = { "usa": { "a": { "min": 1, "max": 2, "avg": 1.5 }, "b": { "min": 3, "max": 5, "avg": 4 } }, "canada": { "c": { "min": 1, "max": 2, "avg": 1.5 } } }; const maxValuesPerCountry = Object.entries(data).reduce( (acc, [key, value]) => ( {...acc, [key]: Object.entries(value).map(([, v]) => v.max) } ), {} ); console.log(maxValuesPerCountry); console.log(`usa: ${maxValuesPerCountry.usa}`);

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