What is Function Composition?

It is an approach where the result of one function is passed on to the next function, which is passed to another until the final function is executed for the final result.

//example
const double = (x) => x * 2;
const square = (x) => x * x;

var output1 = double(2);
var output2 = square(output1);
console.log(output2);

var output_final = square(double(2));
console.log(output_final);