TS Example

blah.ts

const foo = [{
    id: 1,
    name: 'Mike'
}, {
    id: 2,
    name: 'Tom'
}, {
    id: 3,
    name: 'Sally'
}];

function nameLengthGreaterThan(x: number) {
    return (namedThing: {name: string}) => namedThing.name.length > x;
}

const longNames = foo
    .filter(nameLengthGreaterThan(4))
    .map(person => person.name)

console.log(longNames);