Math.random

JavaScript
1 
function RandNum(min, max){
    return Math.floor(Math.random() * (min - max) )

}


Lucky = RandNum(1, 6)

console.log(Lucky)

In console, it goes in negatives from -1 to -5, why?

2

Because min-max is -5 and Math.floor rounds to the nearest integer less than the real number.

1 Like
3

If you need positive numbers, reverse your formula to (max - min)

If you are using ES6, you can shorten the code to:

function RandNum(min, max){
    return ~~(Math.random() * (max - min) )

}
4

A very good example why shorten a code is often not a good solution in case of readable code :wink:

2 Likes
5

I must agree, that hacks such as ~~ are far less preferable to using techniques such as Math.floor() which almost everyone can understand at a glance.

We are not desperate for the few extra characters afforded to us by ~~. Our keyboards and fingers can take the strain :slight_smile:

6

I’m in agreement here with the use of obfuscation — there’s irony in that word I am sure.

That said it’s good to know about these things. The ~~ is a double bit wise not operation.

Some links that maybe useful

As I say I am with the others on this. Would have jumped on it some years ago, but would favour readability now :slight_smile:

edit: I believe what you are looking for is this

function RandNum(min, max){
    return Math.floor(Math.random() * (max - min + 1) + min)
}

Now how readable is that :laughing:

3 Likes
7

Too advance for me, but I will get there in a decade or maybe 3

1 Like
8

and also, why does it go in negatives when doing my form? can you explain?

9

This is simple mathematic.

Min is lower then max. So min - max is a negativ number, if you multiply a positiv random number with a negativ number the result is negative.

1 Like
10

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