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

Predicate Function Check for All Elements

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 
// Define a function called `all` that checks if all elements of an array satisfy a given condition.
const all = (arr, fn = Boolean) => arr.every(fn); // Check if every element in the array satisfies the provided condition

// Example usage
console.log(all([4, 2, 3], x => x > 1)); // Returns true since all elements are greater than 1
console.log(all([4, 2, 3], x => x < 1)); // Returns false since not all elements are less than 1
console.log(all([1, 2, 3])); // Returns true since all elements are truthy

Output:

true
false
true

Flowchart:

Live Demo:

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

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