[FIXED] How to Make Consecutive Numbers from an Array

Issue

I have an array like this

[-2,4,5,6,7,8,10,11,15,16,17,18,21]

Is anyone know, how to make the output from that array become integer like this

-2,4-8,10-11,15-18,21

The output will take the consecutive number become one number

This things is new for me, any help would be appreciated, thanks

Solution

Below I created function for replacing a sequence in an array with a string containing its range. There are three functions.

getConsectiveCount will take array and index as arguments and will get the count of consecutive numbers after that.

replaceFirstConsective will take array and will replace only first sequence in the array.

replaceAllConsectives will replace all the sequences in an array.

const arr = [-2,4,5,6,7,8,10,11,15,16,17,18,21];
const getConsectiveCount = (arr, index) => {
  let count = 0;
  for(let i = index; i < arr.length; i++){
    if(arr[i + 1] === arr[index] + (i - index) + 1){
      count++;
    }
  }
  return count;
}

console.log(getConsectiveCount(arr, 1));
const replaceFirstConsective = (arr) => {
  for(let i = 0; i < arr.length; i++){
    let count = getConsectiveCount(arr,i);
    if(count){
      
  return [...arr.slice(0, i), `${arr[i]}-${arr[i + count]}`, ...arr.slice(i + count + 1)]
    }
  }
  return arr;
  
}
const replaceAllConsectives = (arr) => {
  for(let i = 0; i < arr.length;i++){
    arr = replaceFirstConsective(arr)
  }
  return arr;
}

console.log(JSON.stringify(replaceAllConsectives(arr)))

Answered By - Maheer Ali

Answer Checked By - Mildred Charles (PHPFixing Admin)