Currying article

filter-map-bad-way.js

const items = [{name: 'Bruce' }, {name: 'Fabs'}, {name: 'Bruce'}, {name: 'Gaby'}];
const filter = function(key, value){
  return function(i){
    return i[key] === value;
  }
}
const applier = function(key, value){
  return function(i){
    i[key] = value;
  }
}
const where = filter('name', 'Bruce');
const apply = applier('lastname', 'Wayne');
items.filter(where).map(apply);
console.log(items);

/*
[{ name: 'Bruce', lastname: 'Wayne' },
  { name: 'Fabs' },
  { name: 'Bruce', lastname: 'Wayne' },
  { name: 'Gaby' }]
*/