Create an array alternating between 2 different values

Question

I am trying to create an array alternating between 2 different values with a predetermined length.

Example:

conts value1 = 1;
const value2 = 2; 
cont length = 6; 

//desired output
const array1 = [1, 2, 1, 2, 1, 2];

First, it looks like you have an error in your code "const". Second, could you add the resulting values and the expected values to see what are you trying to achieve? — Andrés Chandía, Mar 17 '20 at 21:13

score 2 · Accepted Answer · answered Mar 17 '20 at 20:59

You can create the array using Array.from with the desired length and map it to have the desired values :

const value1 = 1;
const value2 = 2; 
const length = 6; 

const result = Array.from({ length }).map((e, ndx) => ndx % 2 ? value2 : value1); 

console.log(result);

score 0 · Answer 2 · answered Mar 17 '20 at 20:52

0

Try with:

var repeated = new Array(3).fill([1, 2]).flat();

Or more general:

function repeat(n, value){
    return new Array(n).fill(value).flat();
}

result = repeat(3, [1, 2]);

Credits: https://stackoverflow.com/a/54935305/4628597

answered Mar 17 '20 at 20:52

Alvin Sartor

2,249
4
20
36

score 0 · Answer 3 · answered Mar 17 '20 at 20:58

0

An easy beginner solution would be something like this:

function createArray(value1, value2, length){
    var array = new Array()
    for(var i=0; i<length;i++){ 
          if(i%2 == 0){
           array.push(value1);
          }else{
           array.push(value2);
          }
    return array;
    }
}

answered Mar 17 '20 at 20:58

naman

46
1
5

Thanks, I will dissect this a bit more to see how you did it thank you! – Hdjjannana Mar 17 '20 at 21:12

score 0 · Answer 4 · answered Mar 17 '20 at 21:37

You could take an array of values in the wanted order and use a closure over the index of the values array adjusted by taking the remainder with the length of the values array.

const values = [1, 2],
      length = 6,
      result = Array.from({ length }, (i => _ => values[i++ % values.length])(0)); 

console.log(result);

Create an array alternating between 2 different values

4 Answers4