Immutable JS - converting a collection of Maps to a List

Question

I have the following structure in the project im working on (uses immutable JS):

data :[{name: 'john', surname: 'smith', children: [{name: 'sam'}, {name: 'ben'}]},
       {name: 'jane', surname: 'jones', children: [{name: 'tim'}, {name: 'amy'}]}]

the object is converted to immutable JS via fromJS().

I need a new object in the following structure:

data :[{name: 'john', surname: 'smith', children: ['sam','ben']},
       {name: 'jane', surname: 'jones', children: ['tim','amy']}]

Any pointers much appreciated.

Answer 1

The pure JS answer of Christian doesn't exactly apply to immutable.js objects, so here are a few ways to do it with immutable.js's collection API.

There are more options (e.g. reduce), feel free to check the docs; the method descriptions usually come with examples.

const raw = [{name: 'john', surname: 'smith', children: [{name: 'sam'}, {name: 'ben'}]},
       {name: 'jane', surname: 'jones', children: [{name: 'tim'}, {name: 'amy'}]}];

const data = Immutable.fromJS(raw);

function run(name, operation) {
  let result;
  console.time(name);
  for(let i=0; i < 50000; i++){
    result = operation();
  }
  console.timeEnd(name);
  console.log(result1.toJS());
}


run('simple', () => {
  // simply updating objects inside a mapping
  result1 = data.map(
    person => person.update('children',
      kidObjs => kidObjs.map(
        kid => kid.get('name')
      )
    )
  );
});


run('withMutations and setIn', () => {
  // using withMutations and setIn
  result2 = data.withMutations(list => {
    list.forEach((val, idx) => {
      list.setIn(
        [idx, 'children'],
        val.get('children').map(kid => kid.get('name'))
      )
    });
  });
});

run('withMutations and update', () => {
  // slightly faster by using withMutations set/update
  result2 = data.withMutations(list => {
    list.forEach((val, idx) => {
      list.set(idx, val.update('children', kids => kids.map(kid => kid.get('name'))))
    });
  });
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/immutable/4.0.0-rc.14/immutable.min.js"></script>