js_code_golf_1_3.js

const prime3 = end =>{
  if(end < 2) return [];
  
  const num = [2];
  for(let i = 3; i <= end; i += 2) num.push(i);
  for(let k = 1; k < num.length; k++){
    let curr = num[k], min = curr * curr, i = num.length;
    if(num[i - 1] < min) break;
    while(i--){
      if(num[i] < min) break;
      if(num[i] % curr == 0) num.splice(i, 1);
    }
  }
  return num;
}