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JavaScript: Get a list of elements that exist in both arrays, using a provided comparator function

JavaScript fundamental (ES6 Syntax): Exercise-209 with Solution

Write a JavaScript program to get a list of elements that exist in both arrays, using a provided comparator function.

  • Use Array.prototype.filter() and Array.prototype.findIndex() in combination with the provided comparator to determine intersecting values.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const intersectionWith = (a, b, comp) => a.filter(x => b.findIndex(y => comp(x, y)) !== -1);
console.log(intersectionWith([1, 1.2, 1.5, 3, 0], [1.9, 3, 0, 3.9], (a, b) => Math.round(a) === Math.round(b)));

Sample Output:

[1.5,3,0]

Flowchart:

flowchart: Get a list of elements that exist in both arrays, using a provided comparator function

Live Demo:

See the Pen javascript-basic-exercise-209-1 by w3resource (@w3resource) on CodePen.


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JavaScript: Tips of the Day

How to check whether a string contains a substring in JavaScript?

ECMAScript 6 introduced String.prototype.includes:

const string = "foo";
const substring = "oo";

console.log(string.includes(substring));

includes doesn't have Internet Explorer support, though. In ECMAScript 5 or older environments, use String.prototype.indexOf, which returns -1 when a substring cannot be found: 

var string = "foo";
var substring = "oo";

console.log(string.indexOf(substring) !== -1);

Ref: https://bit.ly/3fFFgZv