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Before we move on to strings, here's a little demo with the math object and a little convenience function

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which you might actually need in many of your programs.

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We have math random to give us a random number,

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now what does math random produce though? It produces a random number between 0 and 1.

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Now that's nice but sometimes you need a random number between 10 and 20,

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what can you do in such a scenario?

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Well we can write our own function that builds up on math random and allows us to provide an upper and

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lower boundary.

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Now for that, I'll create a new function and of course you can create it in any way you want, with a function

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declaration, function expression, arrow function, whatever you need and I'll name it randomIntBetween,

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now of course the name is totally up to you.

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Now here I expect two values, a minimum and a maximum value,

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so my lower and my upper boundary and we want to return a number here.

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Now it all starts with math random but of course, that is between 0 and 1 as we learned and that's not

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what we want here.

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Now to respect our minimum boundary, we can add the minimum,

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if we call this function for example with a value of 5 for min, we now get a random number plus our minimum,

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so we can't get a number lower than min because we add min,

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so we're already respecting our minimum which sounds quite good.

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Now we also of course want to respect the max

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however. Now to respect the max here, we need to multiply our random number here.

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What happens if we multiply it with our maximum? Let's say our minimum is 5, our maximum is 10,

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this gives us a random number between 0 and 1,

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we multiply this with 10,

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So if we have 0 which is of course very unlikely, then we would stick to 0, we add min,

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we have our minimum number, sounds about right.

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If we have one, then we multiply this by max,

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so if our max value was 10,

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now we have 10 and we add 5 to it,

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so now we would have a value of 15 which is above our maximum.

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So we actually need to multiply it with max minus min,

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so only with the range between max and min.

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Now if max is 10 and I can put this here to make it easier to keep in mind,

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so these are the values we're working with in our fictional example to verify the function.

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If min is 5 and max is 10, then this yields 5.

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If random, math random gives us 1, then this overall term produces 1 times 5 equals 5,

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we add 5 to that, we have 10 which is of course our maximum

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so that is all right. Now theoretically, that would be great

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but even though it's not saying it here at the tooltip but you could find it on MDN for example, it's

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important to understand that for the random method here on the math object, 1 is actually not included,

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so the random number we'll get might be 0.99999 but we'll never get a 1.

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So as a result, the biggest number we can get here is max minus min,

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so that's 5, 5 times 0.99999,

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so that's almost 5, plus 5 is almost 10.

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Now if we want to include both the minimum and the maximum here,

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so we want to make sure that both numbers can occur,

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then we're not finished yet because right now this can never yield the maximum because random only yields

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0.99999 and therefore we can only get close to the maximum.

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Now to get the maximum, we can add one here to our multiplication term so that this actually is 6 for these

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values we're providing here and therefore the biggest number we can reach right now is 

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10.99999,

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right,

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because we have six times almost 1,

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so we have almost 6 as a maximum result here, plus min which is 5,

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we have almost 11. Now of course we want to stop at max however which is 10 and not at almost 11

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and now we can leverage another function on the math object and that's the floor function. Floor

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rounds this number down to the nearest integer, so we can wrap this entire term with math floor and it

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will basically just cut the decimal places you could say. So if we had this as a result,

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then floor will turn this into 10

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and now we have a function which yields a number between min and max where both values are included.

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Now of course you can deviate that and you can play around with that and if you google for Javascript,

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random between and so on, you'll find many examples where min is not included, where max is not included

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and so on

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but this here is a pretty common scenario which is why I wanted to show it to you.

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Well and with that if we give it a try and we console log random in between let's say 1 and 10, let's

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see what that gives us.

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If we save that and we go back to our page and reload, now we should get a couple of integers randomly

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but never above 10 or below 1.

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So now we can run this as often as we want,

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we'll never get a number bigger than 10 or smaller than 1.