countDecreasingRatings Amazon SDE2 coding question

countDecreasingRatings.js

function countDecreasingRatings(arr){

    let isDecrease=false;
    let theMap={};
    let chainLength=1;
    for(let x= 0; x<arr.length-1;x++){

        let prev=arr[x];
        let next=arr[x+1];
        if(next<prev){
            if(theMap[chainLength]){
                theMap[chainLength]++
            }else{
                theMap[chainLength]=1;
            }
            chainLength++;
            if(theMap[chainLength]){
                theMap[chainLength]++
            }else{
                theMap[chainLength]=1;
            }
        }else{
            chainLength=1;
        }
    }
    theMap[1]=arr.length
    console.log(theMap);
}


countDecreasingRatings([4,3,5,4,3,2])