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JS Random Number

This lesson is part of How To · All levels

Summary

Math.random() yields a random decimal number from 0 (inclusive) to less than 1. To get an integer in a certain range, multiply by the number of possible values and then round it down and add the minimum value. If a number is used for security like a token, use crypto.getRandomValues(), not Math.random().

Key points

Math.random() always yields 0 <= x < 1 and never exactly 1.
The integers 0 to n-1: Math.floor Math.random() * n).
Inclusive range min to max: Math.floor(Math.random() * (max - min + 1)) + min.
Math.random() is not suitable for security tokens or passwords.

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