Compatible substrings - Two strings are compatible if one string of length "m" is made of of "m" consecutive characters in the second string of length "n" (m<=n).

areStringsCompatible.js

/*
    Author: Shourya Ranka
    Objective: Two strings are compatible if one string of length "m" is made of of "m" consecutive characters in the second string of length "n" (m<=n). 
    1. "facebook", "beo" // compatible - b,e,o are consecutive letters in 'facebook' though the order is different. 
    2. "facebook", "aco" // not compatible - a,c,o are not consective letters present in 'facebook'
*/
const stringSorter = str => str.split('').sort().join('');

const areStringsCompatible = (str1, str2) => {
   if(!(str1 && str2)){
     return false;
   }
   
   let parentStr = str1.length >= str2.length ? str1 : str2;
   let testStr = str1.length <= str2.length ? str1 : str2;
   
   for(let i=0;i<parentStr.length;i++){
      let tmpStr = parentStr.substring(i, i + testStr.length);
      if(stringSorter(tmpStr) == stringSorter(testStr)) {
        return true;
      }
   }
   return false;
}


// Test 1: Checks whichever input string is smaller and determines compatibility
console.log(areStringsCompatible('facebook','beo'));
console.log(areStringsCompatible('beo', 'facebook'));

// Test 2: If strings are same length and have same characters
console.log(areStringsCompatible('facebook', 'abcefkoo'));

// Test 3: Returns false if strings are not compatible
console.log(areStringsCompatible("facebook", "aco"));

// Test 4: Returns false for invalid input
console.log(areStringsCompatible("facebook"));
console.log(areStringsCompatible());
console.log(areStringsCompatible("",""));

Code Execution @ https://codepen.io/sranka2310/pen/poweENW