pick a random item from a javascript array

问题

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?

回答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);

回答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>

回答3:

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

回答4:

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);

来源：https://stackoverflow.com/questions/42211863/pick-a-random-item-from-a-javascript-array

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