Pick a value from JS array and skip it until all the values are displayed

Question

I have an array which consists of 6 values. I am running Math.random to shuffle it. However, it's shuffling the array every time and displaying a value which is repeating. I want to shuffle the array and get 1 unique value. This value should be removed from the array until every other value if fetched. For example, if an array has items 1,2,3,4 and after shuffling it the answer is 3. Now, I want it to exclude the 3 and fetch a new value from 1,2,4.

I


    const params = {
      icon_emoji: ':laughing:'
    };
    var members=['1','2','3','4','5','6','7'];
    var assignee = members[Math.floor(Math.random()*members.length)];

      bot.postMessageToChannel('general', `It's ${assignee}'s turn today!`, params);


}

function results() {


    const params = {
      icon_emoji: ':laughing:'
    };
    bot.postMessageToChannel('general', `Inside results`, params);


}

`I have an array which consists of 6 values` - code shows array with 7 values, not a great start to the question — Jaromanda X, Jul 08 '19 at 01:10
use array.pop or array.shift to remove a value from an array — Jaromanda X, Jul 08 '19 at 01:11

spender · Accepted Answer · 2019-07-08T01:29:10.327

Your definition of "shuffle" is incorrect... Rather than picking random items from an array then having to splice them out of the array, why not actually shuffle (i.e. reorder in random order) the entire array using a Fisher-Yates shuffle then just pop elements out of that array?

The shuffle function below is reproduced from this answer:

function shuffle(array) {
  let currentIndex = array.length,
    temporaryValue, randomIndex;

  // While there remain elements to shuffle...
  while (0 !== currentIndex) {

    // Pick a remaining element...
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex -= 1;

    // And swap it with the current element.
    temporaryValue = array[currentIndex];
    array[currentIndex] = array[randomIndex];
    array[randomIndex] = temporaryValue;
  }

  return array;
}

const myArr = [1, 2, 3, 4, 5, 6];
shuffle(myArr);
while (myArr.length > 0) {
  console.log(myArr.pop());
}

Think twice before attempting to write your own shuffling algorithm... Cleverer people than you or I have badly messed up on this before.

score 1 · Answer 2 · answered Jul 08 '19 at 01:13

You can use array.splice function to remove an item from the array

members.splice(Math.floor(Math.random()*members.length), 1);

Note: If you want to retain your original array, I would recommend you to create a temp array and do the manipulations on that variable

Pick a value from JS array and skip it until all the values are displayed

2 Answers2