CODEWITHSUNDEEP
javascriptarraysstringreturncall
Francis
Francis

Reputation:

JS: Math.random for array

Learning JS this week.

Is it possible to use Math.random to return a random value in an array? Does that value be a string and still work?

Upvotes: 9

Views: 44695

Answers (6)

Chadere Oghenenyoreme
Chadere Oghenenyoreme

Reputation: 83

Yeah it is very possible to do what you're asking

const diceRoll = Array.from({ length: 100 }, (_, i) => {
return i + 1;
});

console.log(Math.random() * diceRoll.length);

The code there, why it works is that Math.random returns a random number between 0 and whatever value we set and the value we set here is diceRoll.length which is 100 so it will return a random value between 0 and 99

console.log(Math.random() * diceRoll.length + 1);

will make it return random value between 0 and 100

Upvotes: 0

Rafael Vaitekaitis
Rafael Vaitekaitis

Reputation: 1

You can use this:

var array = [];
for(i = 0; i < 6; i++) {
array[i] = Math.floor( Math.random() * 60 );
}

if you need a number between 1 and 100, just change Math.random() * 60 to Math.random() * 100.

Upvotes: 0

Francis
Francis

Reputation:

Thanks for all your help.

//My array was setup as such.
var arr = New Array();
arr[0]="Long string for value.";
arr[1]="Another long string.";
//etc...

With your help, and since I know the exact number of values in my array (2), I just did:

var randomVariable = arr[Math.floor(2*Math.random())]

Then output randomVariable how I wish.

Thanks!

Upvotes: 1

Rodrigo
Rodrigo

Reputation: 4395

Read this:

var arr = [1, 2, 3, 4, 5, 6];
var r = arr[Math.floor(Math.random()*a.length)]; // r will store a value from a pseudo-random position at arr.

Upvotes: 3

Jez
Jez

Reputation: 29993

Yes, this is indeed possible. Here's some example code:

<script>
    var arr = new Array('a', 'b', 'c', 'd', 'e');
    document.write("Test " + arr[Math.floor(Math.random() * ((arr.length - 1) - 0 + 1))]);
</script>

Note that Math.floor should be used instead of Math.round, in order to get a uniform number distribution.

Upvotes: 3

Luk&#225;š Lalinsk&#253;
Luk&#225;š Lalinsk&#253;

Reputation: 41306

You can take the floating point number (between 0 and 1, non-inclusive) and convert it to an index to the array (integer between 0 and length of the array - 1). For example:

var a = ['a', 'b', 'c', 'd', 'e', 'f'];
var randomValue = a[Math.floor(a.length * Math.random())];

Upvotes: 27

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