How to iterate through an immutable.js object / map / list

Question

I'm new to immutable.js, and for the life of me I can't figure out how to iterate over the map / list that results form using 'fromJS' on my state object.

How would I go about calculating the total of the cart in the example below? Cart syntax is: {productId: quantity, productId: quantity, productId.. etc

    const INITIAL_STATE = fromJS({
      products: [
        {id: 1, name:'spaghetti', price: 25.00},
        {id: 2, name:'gold', price: 20.00},
        {id: 3, name:'rake', price: 15.00},
        {id: 4, name:'car', price: 10.00},
        {id: 5, name:'falcon', price: 5.00}
      ],
      cart: {1: 4, 3: 7}
    })

How do you iterate through immutable objects here? The methods promoted here are light on detail to my junior eye: https://facebook.github.io/immutable-js/docs/#/List/keys

I think I found a solution, bit of a hack though:

const total = () => {
 let total =0
 state.get('products')
   .filter( p => {
     return state.get('cart')
       .has(p.get('id').toString())
   })
   .map( p => {
     total += state.get('cart')
      .get(p.get('id').toString())
      * p.get('price')
   })
 return total
}

Lee · Accepted Answer · 2016-06-07 07:52:47Z

3

The below will work, it's slightly terser.

const total = state.get('cart').reduce((total, quantity, id) => {
  const price = state.get('products').find(product => product.get('id') == id).get('price');
  total += price * quantity;
  return total;
}, 0);

answered Jun 7, 2016 at 7:52

Lee

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