JavaScript: Perform right-to-left function composition

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

Right-to-Left Function Composition

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
// Define a function 'compose' that takes any number of functions as arguments and returns a new function.
const compose = (...fns) => fns.reduce((f, g) => (...args) => f(g(...args)));

// Define functions 'add5' and 'multiply'.
const add5 = x => x + 5;
const multiply = (x, y) => x * y;

// Create a new function 'multiplyAndAdd5' by composing 'add5' and 'multiply'.
const multiplyAndAdd5 = compose(
  add5,
  multiply
);

// Example usage:
console.log(multiplyAndAdd5(5, 2)); // Output 15

Output:

15

Visual Presentation:

Flowchart:

Live Demo:

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

For more Practice: Solve these Related Problems:

• Write a JavaScript program that composes multiple functions from right to left and returns the composed function.
• Write a JavaScript function that accepts a list of functions and creates a new function that applies them in reverse order.
• Write a JavaScript program that demonstrates right-to-left function composition using array.reduceRight().

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• JavaScript fundamental Exercises Home ↩
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