Combine array of keys and array of values into object

Question

I have an array with labels

columns = ["col1", "col2", "col3", "col4"]

and thousands of arrays with values

values = [ 
    ['value1','value2','value3','value4'],
    ['value1','value2','value3','value4'],
    ['value1','value2','value3','value4'],
    // ...
]

I want to iterate the values and create a single array with this structure:

result = [ 
    { col1: "val1", col2: "val2", col3: "val3", col3: "val4" },
    { col1: "val1", col2: "val2", col3: "val3", col3: "val4" },
    { col1: "val1", col2: "val2", col3: "val3", col3: "val4" },
]

I tried to iterate both and return the object dynamically, but without success:

const columns = ["col1", "col2", "col3", "col4"];
const values = [ 
    ['value1','value2','value3','value4'],
    ['value1','value2','value3','value4'],
    ['value1','value2','value3','value4'],
];

const lastArr = values.map((e) =>
    columns.map((col) => {
        return { col: e[0] };
    })
);

console.log(lastArr);

// or manually 

const raw = values.map(e => 
    columns.map(col => {
        return {
            col1: e[0],
            col2: e[1],
            col3: e[2],
            col4: e[3],
        }
    })
);

console.log(raw);

Neither attempts return the desired result.

trincot · Accepted Answer · 2022-07-21 06:11:35Z

3

You can use Object.fromEntries, like so:

const columns = ["col1", "col2", "col3"];
const values = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9],
    [10, 11, 12]
];

const result = values.map(row =>
    Object.fromEntries(columns.map((col, i) =>
        [col, row[i]]
    ))
)

console.log(result);

answered Jul 21, 2022 at 6:11

trincot

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Comments

derpirscher · Accepted Answer · 2022-07-21 20:09:37Z

1

It would be more understandable if your examples were more consistent and the values were a bit more distinguishable but this should do the trick

values.map(v => Object.fromEntries(columns.map((c,i) => [c, v[i]])));

edited Jul 21, 2022 at 20:09

answered Jul 21, 2022 at 6:11

derpirscher

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1 Comment

Natanael Medina Over a year ago

you forget a final ] bracket : values.map(v => Object.fromEntries(columns.map((c,i) => [c, v[i]])));

Yong Shun · Accepted Answer · 2022-07-21 06:26:52Z

0

Traditional JS way to use .reduce() to transform array to new array (form).

Inner part loop to iterate the column array and current iterated item of values, and next add as key-value pair into an object.

let columns = ["col1",
    "col2",
    "col3",
    "col4"
]

let values = [
    ['value1', 'value2'],
    ['value1', 'value2'],
    ['value1', 'value2']
]

let result = values.reduce((acc, cur) => {
    let obj = {};

    for (let i = 0; i < columns.length; i++)
    {
        obj[columns[i]] = cur[i];
    }

    acc.push(obj);

    return acc;
}, []);

console.log(result);

answered Jul 21, 2022 at 6:26

Yong Shun

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