Mastering Immutable.js

Computing new values

You can pass iteratee functions to map() that compute new values. Let's implement a function that capitalizes the string that's passed to it:

const capitalize = s =>  `${s.charAt(0).toUpperCase()}${s.slice(1)}`;

This function will make the first character of any string uppercase. Let's use this as part of an iteratee function passed to map() to help generate a list of names:

const myList = List.of(  Map.of('first', 'joe', 'last', 'brown', 'age', 45),  Map.of('first', 'john', 'last', 'smith', 'age', 32),  Map.of('first', 'mary', 'last', 'wise', 'age', 56));const myMappedList = myList.map(  v => [    capitalize(v.get('first')),    capitalize(v.get('last'))  ].join(' '));console.log('myList', myList.toJS());// -> myList [ { first: 'joe', ...