pick a random item from a javascript array

Question

I am making a bot that can respond to my messages.

If i send Hi! to the bot, it will answer With Well, hello there!. I was just wondering, what do I do to give the bot multiple choices of answers? Is there a way to pick a random item from a responses array using JavaScript?

Answer 1

Use Math.random * the length of the array, rounded down, as an index into the array.

Like this:

var answers = [
  "Hey",
  "Howdy",
  "Hello There",
  "Wotcha",
  "Alright gov'nor"
]

var randomAnswer = answers[Math.floor(Math.random() * answers.length)];

console.log(randomAnswer);

Answer 2

You can use the _.sample method in lodash:

var responses = ["Well, hello there!", "Hello", "Hola", "Yo!", "What’s up?", "Hey there."];
console.log(_.sample(responses));

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>

Answer 3

I can think of two ways:

Method 1:

• Use Math.random() function to get the random number between(0-1, 1 exclusive).
• Multiply it by the array length to get the numbers between(0-arrayLength).
• Use Math.floor() to get the index ranging from(0 to arrayLength-1).

const answers = [ "Hey", "Howdy", "Hello There", "Wotcha", "Alright gov'nor" ]; const randomlyPickedString=answers[Math.floor(Math.random() * answers.length)]; console.log(randomlyPickedString);

Method 2:

• The random(a, b) method is used to generates a number between(a to b, b exclusive).
• Taking the floor value to range the numbers from (1 to arrayLength).
• Subtract 1 to get the index ranging from(0 to arrayLength-1).

const answers = [ "Hey", "Howdy", "Hello There", "Wotcha", "Alright gov'nor" ] ;
const randomlyPickedString=answers[Math.floor(random(1, 5))-1]; console.log(randomlyPickedString);

For ease of understanding the code, I have written created an extra variable(randomlyPickedString). You can use the code without it too.

Answer 4

There's no JavaScript "command" that allows you to do this. But what you can do, is pick an integer at random from 0 to the length of the array, and get the array of responses at that index:

var response = responses[ parseInt( Math.random() * responses.length ) ];

A more concise way to do this is:

var response = responses[ Math.random() * responses.length |0 ];

where | 0 indicates the bitwise-or with 0, which in this case just turns a floating point number (Math.random() returns values from 0 to 1) into its lowest integer

Answer 5

You would first need an array of possible responses. Something like this:

var responses = ["Well hello there!","Hello","Hola!"];

You can then use the Math.random function. This function returns a decimal < 1, so you will need to convert it to an integer.

var responses = ["Well hello there!","Hello","Hola!"];
var responseIndex = Math.floor((Math.random() * 10) + 1);

Also, use the modulus (%) operator to keep your random number within the confines of your array indexes:

var responses = ["Well hello there!","Hello","Hola!"];
var totalResponses = responses.length;
var responseIndex = Math.floor((Math.random() * 10) + 1) % totalResponses;

Finally, lookup your random response in the array:

var responses = ["Well hello there!","Hello","Hola!"];
var totalResponses = responses.length;
var responseIndex = Math.floor((Math.random() * 10) + 1) % totalResponses;
var response = responses[responseIndex];
alert(response);