startAndStopPosition.js

const startAndStopPosition = (nums, val) => {
    if(!Array.isArray(nums) || nums.length === 0) return [-1, -1];
    
    // Initialization of Variables
    let initialIndex = 0;
    let count = 0;
    let startAndStop = [];

    // Looping through the array;
    for(let i = 0; i < nums.length; i++) {
        if(nums[i] < val) {
            initialIndex += 1;
        }
        if(nums[i] === val) {
            count += 1;
        }
    }

   if(count === 0) {
       startAndStop.push(-1, -1);
   }else {
       startAndStop.push(initialIndex, (count - 1) + initialIndex);
   }
    
   return startAndStop;
}

Thank you so much @meekg33k this really helped open my mind.......

Looking forward to the next challenge