Check if a string is sorted in JavaScript

We are required to write a JavaScript function that takes in a string and checks whether it is sorted or not.

For example −

isSorted('adefgjmxz')  // true
isSorted('zxmfdba')     // true
isSorted('dsfdsfva')     // false

Example

Following is the code −

const str = 'abdfhlmxz';
const findDiff = (a, b) => a.charCodeAt(0) - b.charCodeAt(0);
const isStringSorted = (str = '') => {
   if(str.length  0){
         res += 'u';
      }else if(findDiff(str[i+1], str[i]) 
Output
This will produce the following output in console −
true