w3resource

JavaScript: Get removed elements from the end of a given array until the passed function returns true

JavaScript fundamental (ES6 Syntax): Exercise-129 with Solution

Write a JavaScript program to get removed elements from the end of a given array until the passed function returns true.

  • Create a reversed copy of the array, using the spread operator (...) and Array.prototype.reverse().
  • Loop through the reversed copy, using a for...of loop over Array.prototype.entries() until the returned value from the function is falsy.
  • Return the removed elements, using Array.prototype.slice().
  • The callback function, fn, accepts a single argument which is the value of the element.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const takeRightWhile = (arr, func) => {
  for (let i of arr.reverse().keys())
    if (func(arr[i])) return arr.reverse().slice(arr.length - i, arr.length);
  return arr;
};

console.log(takeRightWhile([1, 2, 3, 4], n => n < 3));

Sample Output:

[3,4]

Flowchart:

flowchart: Get removed elements from the end of a given array until the passed function returns true

Live Demo:

See the Pen javascript-basic-exercise-129-1 by w3resource (@w3resource) on CodePen.


Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript program to get removed elements of a given array until the passed function returns true.
Next: Write a JavaScript program to remove n elements from the end of a given array.

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]]