Remove Array Elements Until Condition Is Met

Introduction

In this lab, we will be exploring the concept of removing array elements until a certain condition is met. We will be using the takeUntil function, which loops through an array and removes elements until a specified condition is true. Through this lab, you will gain a deeper understanding of how to manipulate arrays in JavaScript.

Skills Graph

Removing Array Elements Until a Condition is Met

To remove elements in an array until a condition is met and get the removed elements, follow the steps below:

• Open the Terminal/SSH and type node to start practicing coding.
• Loop through the array using a for...of loop over Array.prototype.entries() until the function passed as an argument returns a truthy value.
• Use Array.prototype.slice() to return the removed elements.
• The callback function, fn, accepts a single argument which is the value of the element.

Here's an example code snippet:

const takeUntil = (arr, fn) => {
  for (const [i, val] of arr.entries()) if (fn(val)) return arr.slice(0, i);
  return arr;
};

takeUntil([1, 2, 3, 4], (n) => n >= 3); // [1, 2]

In the above example, the takeUntil() function is used to remove elements in the [1, 2, 3, 4] array until the value is greater than or equal to 3. The output is [1, 2].

Summary

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