Prepend Function Arguments in JavaScript

Introduction

In this lab, we will explore the concept of function partials in JavaScript and learn how to create a higher-order function that allows us to easily prepend arguments to a given function. Through practical examples and exercises, we will understand how partial functions work and how they can be used to simplify our code and make it more modular.

Function Arguments Prepended with Partial

To begin practicing coding, open the Terminal/SSH and enter node.

The function partial is used to create a new function that calls fn with partials as the first arguments.

Use the spread operator (...) to prepend partials to the list of arguments of fn.

const partial =
  (fn, ...partials) =>
  (...args) =>
    fn(...partials, ...args);

const greet = (greeting, name) => greeting + " " + name + "!";
const greetHello = partial(greet, "Hello");
greetHello("John"); // 'Hello John!'

Summary

Congratulations! You have completed the Prepend Function Arguments lab. You can practice more labs in LabEx to improve your skills.