w3resource

JavaScript: Return true if the provided predicate function returns false for all elements in a collection, false otherwise

JavaScript fundamental (ES6 Syntax): Exercise-91 with Solution

Write a JavaScript program that will return  true if the provided predicate function returns false for all elements in a collection, false otherwise.

  • Use Array.prototype.some() to test if any elements in the collection return true based on fn.
  • Omit the second argument, fn, to use Boolean as a default.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const none = (arr, fn = Boolean) => !arr.some(fn);
console.log(none([0, 1, 3, 0], x => x == 2));
console.log(none([0, 0, 0]));

Sample Output:

true
true

Flowchart:

flowchart: Return true if the provided predicate function returns false for all elements in a collection, false otherwise

Live Demo:

See the Pen javascript-basic-exercise-91-1 by w3resource (@w3resource) on CodePen.


Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript program to nest a given flat array of objects linked to one another recursively.
Next: Write a JavaScript program to create a function that gets the argument at index n. If n is negative, the nth argument from the end is returned.

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]]