Closure and higher-order function example

closure-higher-order-example.js

// example of a higher order function: .map() on arrays, map expects a function callback
[1,2,3].map(num => num + 1); // [2, 3, 4];

// closures in es5 syntax
function getValue(property) {
    return function(obj) {
        return obj && obj[property];
    }
}

// closures in es6/2015 syntax
const getValue = property => obj => obj && obj[property];

// our example object
const userInfo = {
    name: 'sarah',
    id: '12345',
    country: 'Australia',
};

// invocation of our closure
getValue('name')(userInfo); // Result: 'sarah'

// an example of our closure combined with a higher order function
const addMe = x => y => x + y;
[1, 2, 3].map(addMe(1)); // [2, 3, 4];