Iterate over array of objects and change one property in each object

Question

I find myself presented with this pattern quite a bit. I have an array of objects that I get back from my api, and I need to manipulate just one of the properties in all of the objects.

Is there a way using ES6/Babel or Typescript to get that pattern to be a little more declarative?

Looking for some neat destructuring trick or something along those lines.

const data = [{ foo: 1, bar: 2}, 
              { foo: 2, bar: 3},
              { foo: 3, bar: 4}];

const increment = a => a + 1;

// Here is my typical pattern
const result = data.map(o => {
    o.foo = increment(o.foo);
    return o;
})

console.log(result);

Answer 1

Object spread (...), available in Babel using the Stage 3 preset, does the trick:

const data = [
  { foo: 1, bar: 2 }, 
  { foo: 2, bar: 3 },
  { foo: 3, bar: 4 },
];

const increment = a => a + 1;

const result = data.map(o => ({ ...o, foo: increment(o.foo) }));
console.log(result);

Answer 2

This is a little more elegant I think - Object.assign is a good way to update an item in an object

const data = [{
  foo: 1,
  bar: 2
}, {
  foo: 2,
  bar: 3
}, {
  foo: 3,
  bar: 4
}];

const increment = a => a + 1;

// Here is my typical pattern
const result = data.map(o => Object.assign(o, {foo: increment(o.foo)}))

console.log(result);