CODEWITHSUNDEEP
node.jsrandom
Cisplatin
Cisplatin

Reputation: 2998

Generate a random number with the largest range in Node.js?

I want to generate uniform random numbers in Node.js with the largest range possible. What's the best way to go about doing this?

(By "largest possible" I mean something like 2^64 possibilities, not an infinite number of possibilities).

Upvotes: -1

Views: 1956

Answers (2)

idbehold
idbehold

Reputation: 17168

Slight modification of @user162097's answer

var getRandomIntWithLargestRange = () => Math.floor(
  Number.MAX_SAFE_INTEGER * (2 * (Math.random() - 0.5))
);

// example
document.write(getRandomIntWithLargestRange());

Upvotes: 0

user162097
user162097

Reputation: 1258

You can use the Number object's MAX_SAFE_INTEGER property, which was introduced in ES6 (there's also a polyfill for older versions of Node here) and gives the largest integer that will not collide with any other as the underlying numerical representation system loses accuracy. If, for whatever reason, you don't care about collisions, you could use the much larger MAX_VALUE property on the same object. This is what I'd do:

// function declaration using ES6 arrow/lambda syntax
var getMaxRandomInt = () => Math.floor(Number.MAX_SAFE_INTEGER * Math.random());
// equivalent to the following:
// function getMaxRandomInt() { return Math.floor(Number.MAX_SAFE_INTEGER * Math.random()); }

// example
document.write(getMaxRandomInt());

Note that, though the distribution is uniform, most results will contain the same number of digits (or the same exponent, in scientific form) as the upper bound, given that there are many more large values than small. If you want to return a float, then you can just remove the Math.floor function (though, functionally, there won't be much difference with large values, especially since all numbers are ultimately stored as floats in JavaScript).

Upvotes: 0

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