Generate Until Condition Is Met

Introduction

In this lab, we will explore the concept of generators in JavaScript. Specifically, we will learn how to create a generator function that produces new values until a certain condition is met. Through hands-on coding exercises, we will gain a better understanding of how generators work and how they can be used to simplify our code and improve its performance.

Skills Graph

Generating Values Until a Given Condition is Met

To start practicing coding, open the Terminal/SSH and type node. Once you have done that, you can create a generator that produces new values until a given condition is met.

To create this generator, follow these steps:

• Initialize the current val using the seed value.
• Use a while loop to keep iterating while the condition function, called with the current val, returns false.
• Use the yield keyword to return the current val and, optionally, receive a new seed value, nextSeed.
• Use the next function to calculate the next value from the current val and the nextSeed.

Here's an example code snippet:

const generateUntil = function* (seed, condition, next) {
  let val = seed;
  let nextSeed = null;
  while (!condition(val)) {
    nextSeed = yield val;
    val = next(val, nextSeed);
  }
  return val;
};

You can use the generator by calling it with the appropriate arguments. For example:

[
  ...generateUntil(
    1,
    (v) => v > 5,
    (v) => ++v
  )
]; // [1, 2, 3, 4, 5]

This will produce an array of values from 1 to 5, since the condition v > 5 is met when val equals 6.

Summary

Congratulations! You have completed the Generate Until Condition Is Met lab. You can practice more labs in LabEx to improve your skills.