construct a object from array and achieve tab completion

Question

need to use values from an array as keys to create a new object.

And need to achieve tap completion.

const keys = ['name', 'age', 'contact', 'response'];
let obj = {};
keys.forEach(key => {
    obj[key] = row[key];
});
obj. //need to know what are the properties previously added.

Typescripts need to understand the object's name, age, and contact properties.

Answer 1

// `as const` makes strings be string literals
const keys = ['name', 'age', 'contact', 'response'] as const;
// theese are the keys union ('name' | 'age' | ...)
type KeyType = typeof keys[number]
// row has data on what object will be
type RowType = typeof row
// the `obj` is the copy of `row` with only `keys` keys
type FullObjType = Pick<RowType, KeyType>
// the `obj` properties are not set yet
type ObjType = Partial<FullObjType>

let obj: ObjType = {};
for (let k of keys) {
  obj[key] = row[key]
}
let fullObj: FullObjType = obj;

Or the other way,

function PickKeys<T, K extends keyof T>(row: T, keys: K[]) {
   return Object.fromEntries(keys.map(k => [k, row[k]])) as Pick<T, K>
}