How to generate random words in JavaScript? [duplicate]

Question

Possible Duplicate:
Getting a random value from a JavaScript array

OK, so I have three variables here, each being rock, paper or scissors. Using JavaScript, how can I generate one of those words randomly?

So far it's like so:

<!DOCTYPE html>
<html>
    <body>
        <button type="button" onclick="myFunction()"> Click me</button>

        <script>
            function myFunction()
            {
                var c="Rock";
                var d="Paper";
                var e="Scissors";
            }
        </script>
    </body>
</html>

Then I'll have a variable called K, which will be the random word out of rock paper or scissors. So it'll be like so:

alert("The computer chose: " + k);

So how can I make JavaScript select randomly between the three variables, c, d and e?

Put them in an array then select a random index from the array. (Please look up the emphasized words.) — user166390
– user166390, Commented Nov 5, 2012 at 17:40
Given that OP didn't have an array in his question, I don't think the duplicate is well chosen (this being said, there are probably other similar questions). — Denys Séguret
– Denys Séguret, Commented Nov 6, 2012 at 13:32

Peter Mortensen · Accepted Answer · 2017-03-04 21:43:08Z

35

Use:

var things = ['Rock', 'Paper', 'Scissor'];
var thing = things[Math.floor(Math.random()*things.length)];
alert('The computer chose:' + thing);

Demonstration

Just to precisely answer your question, supposing you really want to keep your three global variables, you could do this:

var c = "Rock";
var d = "Paper";
var e = "Scissors";
var thing = window['cde'.charAt(Math.floor(Math.random()*3))];
document.write('The computer chose: ' + thing);

Demonstration

(But don't.)

edited Mar 4, 2017 at 21:43

Peter Mortensen

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answered Nov 5, 2012 at 17:41

Denys Séguret

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Comments

Halcyon · Accepted Answer · 2012-11-05 17:42:15Z

4

You can use Math.random() to get a random number beteween 0 and 1.

If you want a whole random number between 0 and 2. (so: 0, 1 or 2). You can use:

Math.floor(Math.random()*3);

Note that Math.round (instead of floor) would be wrong here since the edge values will have a lower chance, and you might actually get 3 as well.

answered Nov 5, 2012 at 17:42

Halcyon

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Comments

Cameron · Accepted Answer · 2021-07-06 22:43:31Z

1

You should make an array:

var words = ['Rock', 'Paper', 'Scissors'];

and then generate a random number between 0 and the length of the array, with 0 decimals:

var number = Math.floor(Math.random() * words.length);

And then select the word where the key is the random number you just created:

var word = words[number];

In total:

var words = ['Rock', 'Paper', 'Scissors'];
var word = words[Math.floor(Math.random() * words.length)];

edited Jul 6, 2021 at 22:43

Cameron

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answered Nov 5, 2012 at 17:44

Wouter J

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2 Comments

Matthew Over a year ago

-1 is not necessary. If you add that, it would never return Scissors and instead return undefined.

Cameron Over a year ago

If fact, if you leave the -1 in the code, you will get NaN results about 1/words.length proportion of the time. I have removed the -1 from the short summary at the end.

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