w3resource

JavaScript: Perform right-to-left function composition

JavaScript fundamental (ES6 Syntax): Exercise-66 with Solution

Write a JavaScript program to perform right-to-left function composition.

  • Use Array.prototype.reduce() to perform right-to-left function composition.
  • The last (rightmost) function can accept one or more arguments; the remaining functions must be unary.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const compose = (...fns) => fns.reduce((f, g) => (...args) => f(g(...args)));
const add5 = x => x + 5;
const multiply = (x, y) => x * y;
const multiplyAndAdd5 = compose(
  add5,
  multiply
);
console.log(multiplyAndAdd5(5, 2)); 

Sample Output:

15

Pictorial Presentation:

JavaScript Fundamental: Perform right-to-left function composition

Flowchart:

flowchart: Perform left-to-right function composition

Live Demo:

See the Pen javascript-basic-exercise-66-1 by w3resource (@w3resource) on CodePen.


Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript program to add special characters to text to print in color in the console (combined with console.log()).
Next: Write a JavaScript program to perform left-to-right function composition.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



JavaScript: Tips of the Day

Chunks an array into n smaller arrays

Example:

const tips_chunkIntoN = (arr, n) => {
  const size = Math.ceil(arr.length / n);
  return Array.from({ length: n }, (v, i) =>
    arr.slice(i * size, i * size + size)
  );
}
console.log(tips_chunkIntoN([1, 2, 3, 4, 5, 6, 7,8], 4)); 

Output:

[[1,2],[3,4],[5,6],[7,8]]