Loop in const object

Question

I am trying to do the following:

const obj {
    for(i=0;i<data.length;i++){
       Key[i]: data[i].description
    }
}

(I know I probably also needs to add a comma at the end of each line except on the last one, but I already get errors in the earlier stage)

This doesn't seem to be allowed in JS. Are there any alternatives? Thank you!

Answer 1

You could use Object.assign in combination with spread syntax ... and map the single objects with Array#map and use computed property names for the object.

const obj = Object.assign(...data.map((o, i) => ({ ['Key' + i]: o.description })));

Answer 2

It looks like you're trying to create an object from a keys array and a data array.

A clean approach would be to use array reduction:

const obj = data.reduce((obj, d, i) => {
  obj[Key[i]] = d.description;
  return obj;
}, {});

which, assuming your environment allows it, can be simplified further (due note that this will be cleaner code but less efficient because the object spread copies the entire object every time):

const obj = data.reduce((obj, d, i) => ({
  ...obj,
  [Key[i]]: d.description
}), {});

but you could also use a simple for loop:

const obj = {};
for (let i = 0; i < data.length; i++) {
  obj[Key[i]] = data[i].description;
}

Note: The code above will break if Key.length !== data.length.