如何在 JavaScript 中获取随机列表项

Question

I am using discord.py to make a Discord bot that gives you a complement every 24 hours. To test, I set the timer to 1 second. The code I made looked like this:

const Discord = require('discord.js')
const client = new Discord.Client()

const complements = [
    ...
]

client.once('ready', () => {
    console.log('Logged in!');
    client.user.setActivity("with nice complements.")
    setInterval(console.log,1000,complements[Math.floor(Math.random() * (complements.length - 1))]);
});

However, this just returns the same complement every time. Is there any ways it can choose a random complement?

Answer 1

The parameters you pass to setInterval are evaluated at the time when you pass them to the setInterval function not at each execution of it.

So this: setInterval(console.log,1000,complements[Math.floor(Math.random() * (complements.length - 1))]);

is equal to:

let complement = complements[Math.floor(Math.random() * (complements.length - 1))];
setInterval(console.log,1000, complement);

You need to pass a callbnack function to setInterval that is executed, and move you random access there.

setInterval(() => {
   console.log(complements[Math.floor(Math.random() * (complements.length - 1))])
}, 1000)

Answer 2

Try to use setInterval like this:

setInterval(() => {
  const value = complements[Math.floor(Math.random() * (complements.length - 1))];
  console.log(value);
},1000);

Answer 3

Rather than pass a fixed argument to console.log in each iteration (I'd actually never seen setInterval called with more than 2 parameters before and had to look up what it meant:-)), pass a function which, when called, generates a new random value and passes that to console.log :

 setInterval(() => {
    const complement = complements[Math.floor(Math.random() * (complements.length - 1)) ] ;
    console.log(complement);
 }, 1000)

Answer 4

Problem is setInterval. He call the function with the same result. Try it and check console

 let x = setInterval(console.log(Math.random()),1000,); let num = 0; let y = setInterval(() => { console.log(num) num += 1 },1000,);