Run results for: Intersection of multiple sorted arrays | All positive, Max number isn't large | Lodash _.intersection() vs Various custom optimized methods

Test name	Executions per second
✓ Custom optimized function 3 (Best for reasonable max)	45,753 Ops/sec
Custom optimized function 1 (Best for arbitrary numbers)	7,608 Ops/sec
Lodash _.intersection()	5,890 Ops/sec
Custom optimized function 2	3,744 Ops/sec

Script Preparation code:

var arr1 = [];
var arr2 = [];
var arr3 = [];
var arr4 = [];

for (i = 0; i < 1000; i++) {
    arr1.push(getRandom());
    arr2.push(getRandom());
    arr3.push(getRandom());
    arr4.push(getRandom());

    arr1.sort();
    arr2.sort();
    arr3.sort();
    arr4.sort();
}

function getRandom() {
    const minimum = 1;
    const maximum = 1000;
    var randomnumber = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
    return randomnumber;
}

Tests:

Lodash _.intersection()
const results = new Set(_.intersection(arr1, arr2, arr3, arr4));
Custom optimized function 1 (Best for arbitrary numbers)
function intersectMultipleArrays(...arrays) { if (arrays.length === 0) return new Set(); // Sort arrays by length to optimize operations arrays.sort((a, b) => a.length - b.length); // Start with the smallest array as the base intersection set let intersection = new Set(arrays[0]); // Iterate over the remaining arrays and filter the intersection for (let i = 1; i < arrays.length; i++) { intersection = new Set(arrays[i].filter(item => intersection.has(item))); // Early exit if intersection is empty if (intersection.size === 0) return new Set(); } // Return the final Set return intersection; } const results = intersectMultipleArrays(arr1, arr2, arr3, arr4);
Custom optimized function 2
const results = new Set( [arr1, arr2, arr3, arr4] .sort((a, b) => b.length - a.length) .reduce((a, b) => a.filter(aValue => b.includes(aValue))) );
Custom optimized function 3 (Best for reasonable max)
function intersectMultipleArraysRevised(...arrays) { let maximum = -1; for (let i = 0; i < arrays.length; i++) { for (let j = 0; j < arrays[i].length; j++) { const num = arrays[i][j]; if (num > maximum) { maximum = num; } } } const count = new Array(maximum + 1).fill(0); for (let i = 0; i < arrays.length; i++) { for (let j = 0; j < arrays[i].length; j++) { const num = arrays[i][j]; count[num]++; } } const result = new Set(); const arrLen = arrays.length; for (let i = 0; i <= maximum; i++) { if (count[i] === arrLen) { result.add(i); } } return result; } const results = intersectMultipleArraysRevised(arr1, arr2, arr3, arr4);

Run results for: Intersection of multiple sorted arrays | All positive, Max number isn't large | Lodash _.intersection() vs Various custom optimized methods

Lodash _.intersection()

Custom optimized function 1 (Best for arbitrary numbers)

Custom optimized function 2

Custom optimized function 3 (Best for reasonable max)