const strng= "ABCGAG"; function getOccurence(str){ let arr= str.split(''); let counter=0; for(let i=0;i<arr.length;i++){ console.log(arr[i]); if(arr[i]==='A'){ for(let j=i+1;j<arr.length;j++){ if(arr[j]==='G'){ counter++ } } } } console.log('final countr',counter); } getOccurence(strng);