w3resource

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

JavaScript fundamental (ES6 Syntax): Exercise-16 with Solution

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

  • Use Array.prototype.every() to test if all 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 all = (arr, fn = Boolean) => arr.every(fn);
console.log(all([4, 2, 3], x => x > 1)); 
console.log(all([4, 2, 3], x => x < 1));
console.log(all([1, 2, 3])); 

Sample Output:

true
false
true

Flowchart:

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

Live Demo:

See the Pen javascript-basic-exercise-1-16 by w3resource (@w3resource) on CodePen.


Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript program to return the minimum-maximum value of an array, after applying the provided function to set comparing rule.
Next: Write a JavaScript program to split values of two given arrays into two groups. If an element in filter is truthy, the corresponding element in the collection belongs to the first group; otherwise, it belongs to the second group.

What is the difficulty level of this exercise?

Test your Programming skills with w3resource's quiz.



Follow us on Facebook and Twitter for latest update.