JavaScript: Filter out all values from an array for which the comparator function does not return true

JavaScript fundamental (ES6 Syntax): Exercise-74 with Solution

Filter Array by Comparator

Write a JavaScript program to filter out all values from an array for which the comparator function does not return true.

• Use Array.prototype.filter() and Array.prototype.findIndex() to find the appropriate values.
• Omit the last argument, comp, to use a default strict equality comparator.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2
// Define a function 'differenceWith' to find the difference between two arrays based on a provided comparison function.
const differenceWith = (arr, val, comp) =>
  // Filter array 'arr' to keep only those elements for which no element in array 'val' satisfies the comparison function 'comp'.
  arr.filter(a => val.findIndex(b => comp(a, b)) === -1);

// Example usage:
console.log(differenceWith([1, 1.2, 1.5, 3, 0], [1.9, 3, 0], (a, b) => Math.round(a) === Math.round(b)));

Output:

[1,1.2]

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-74-1 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript program that filters an array by keeping only the values that pass a custom comparator function.
• Write a JavaScript function that iterates over an array and excludes elements for which the comparator returns false.
• Write a JavaScript program that applies a comparator to each array element and returns a new array with elements meeting the criteria.

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