javascript for loop to achieve particular output?

Question

How would I get a standard for loop to output in pairs or other groups (like three's of four's) with the output shifting up one after the last digit of the group?

for(var i = 0: i < 8; i++){
  console.log(i)
}

so instead of the output being; 0,1,2,3,4,5,6,7

In pairs it would be; 0,1,1,2,2,3,3,4

or if it went up in groups of four; 0,1,2,3,1,2,3,4

I did try doing something like this, but instead of going up in two's every time I need the loop to output the first 2 digits move up one then output the next two ect...

 for(var i = 0: i < 8; i+= 2){
      console.log(i)
    }

Hope that makes sense

Is there a problem with nesting a second loop?

גלעד ברקן
– גלעד ברקן

2021-03-15 13:01:07 +00:00
Commented Mar 15, 2021 at 13:01 — גלעד ברקן
– גלעד ברקן, Commented Mar 15, 2021 at 13:01

trincot · Accepted Answer · 2021-03-15 12:03:29Z

1

For each case you would need to come up with the right formula based on i:

so instead of the output being; 0,1,2,3,4,5,6,7 In pairs it would be; 0,1,1,2,2,3,3,4

for (let i = 1; i < 9; i++) {
    console.log(i >> 1); // this bit shift is integer division by 2
}

or if it went up in groups of four; 0,1,2,3,1,2,3,4

for (let i = 0; i < 8; i++) {
    // Perform division by 4 and add remainder to that integer quotient
    console.log((i >> 2) + (i % 4)); 
}

answered Mar 15, 2021 at 12:03

trincot

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Comments

Jens Ingels · Accepted Answer · 2021-03-15 12:33:13Z

0

You could work with a variable inside the loop to determine the index. This way you can specify how many times you want the loop to run:

for(let index = 0; index < 8; index++) {
    const currentIndex = index - (index >> 1);
    console.log(currentIndex);
}

It also makes it easy to implement it as immutable:

const array = new Array(8).fill(0).map((entry, index) => index - (index >> 1));
console.log(array);

answered Mar 15, 2021 at 12:33

Jens Ingels

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Comments

Lakshya Thakur · Accepted Answer · 2021-03-15 17:17:16Z

0

I think a function like below where we specify the total n and the chunksize after which you want to increase a single step might work for us :-

function getByChunkSteps(n,chunkSize){
let step = -1;
let output = [];
for(let index = 0;index < n;index++){
  if(index%chunkSize===0){
  step+=1;
  }
    output.push((index%chunkSize)+step);
}
return output;
}

console.log(getByChunkSteps(10,2));
console.log(getByChunkSteps(8,4));
console.log(getByChunkSteps(9,3));

edited Mar 15, 2021 at 17:17

answered Mar 15, 2021 at 12:10

Lakshya Thakur

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