CODEWITHSUNDEEP
javascript
TheLazyChap
TheLazyChap

Reputation: 1902

JavaScript Number MIN_VALUE how does it work?

I'm writing a simple function in Javascript that returns the largest in an array of numbers and I have a bunch of test data but I cannot for the life of me figure out why 2 of the tests failed.

My largest in list function:

function largestInList(list) {

    var largest = Number.MIN_VALUE;

    for (var i = 0; i < list.length; i++) {
        if (largest <= list[i])
            largest = list[i];
    }

    return largest;
}

My Tests

it("Return the largest in a list", function() {

        expect(largestInList).toBeDefined();
        expect(largestInList([])).toEqual(Number.MIN_VALUE);
        expect(largestInList([-11])).toEqual(-11);
        expect(largestInList([-1, -3])).toEqual(-1);
        expect(largestInList([3, -1])).toEqual(3);
        expect(largestInList([3, -1, 8])).toEqual(8);
        expect(largestInList([4, 9, -1, 9, 8])).toEqual(9);
        expect(largestInList([3, 61, 8])).toEqual(61);
        expect(largestInList([3, 61, 8, 333, -1])).toEqual(333);

});

These two lines failed but I cannot figure out why?

expect(largestInList([-11])).toEqual(-11);

expect(largestInList([-1, -3])).toEqual(-1);

Error:

Expected 5e-324 to equal -11

Expected 5e-324 to equal -1

I'm not a math person but if my assumption is correct -11 < -1 and 5e-324 => 5 x 10 raised to the power of -324 (which technically should be a lot smaller than -11 or -1)

Upvotes: 1

Views: 307

Answers (1)

Dave Newton
Dave Newton

Reputation: 160251

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/MIN_VALUE

The Number.MIN_VALUE property represents the smallest positive numeric value representable in JavaScript.
[...]
The MIN_VALUE property is the number closest to 0, not the most negative number, that JavaScript can represent.

5e-325 isn't a negative number.

Maybe negative infinity instead? It kind of depends on what you're doing with the result.

Upvotes: 1

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