Map closure

mapClosure.js

// Make our function useful within a mapping function:

const prefix = prefix => value => `${prefix}${value}`;

// our function takes a prefix string, then returns a function which takes value, 
// which then returns a string with the prefix and value together.

const animals = ['dog', 'cat', 'bird', 'giraffe'];

animals.map(prefix('super '); // result: ['super dog', 'super cat', 'super bird'];

// Alternatively, we could also name our outer function for clarity:
const prefixSuper = prefix('super ');

animals.map(prefixSuper); // result: ['super dog', 'super cat', 'super bird'];