Find longest word in dictionary that is a subsequence of a given string

Google interview: Longest word in Dictionary (javaScript)

##The Challenge
Given a string S and a set of words D, find the longest word in D that is a subsequence of S.

Word W is a subsequence of S if some number of characters, possibly zero, can be deleted from S to form W, without reordering the remaining characters.

Note: D can appear in any format (list, hash table, prefix tree, etc.

For example, given the input of S = "abppplee" and D = {"able", "ale", "apple", "bale", "kangaroo"} the correct output would be "apple"

The words "able" and "ale" are both subsequences of S, but they are shorter than "apple".
The word "bale" is not a subsequence of S because even though S has all the right letters, they are not in the right order.
The word "kangaroo" is the longest word in D, but it isn't a subsequence of S.
Learning objectives
This question gives you the chance to practice with algorithms and data structures. 
It’s also a good example of why careful analysis for Big-O performance is often worthwhile, as is careful exploration of common and worst-case input conditions.


## ONE ANSWER 
function searchString (String='', Dictionary=[]) {
  // sort dictionary by length
  Dictionary.sort((a,b) => { return b.length - a.length })
  
  // verify word in substring
  function hasSubString(word, str) {
    let head = 0;
    if (word.length === 0) {
      return false
    }
    for (let i = 0; i < word.length ; i += 1) {
      let index = str.indexOf(word[i],head);
      if (index < 0 || head > str.length) {
        return false
      }
      head = index + 1;
    }
      return true
  } 
  
  // cycle through dictionary, in order of length
  
  for (let i = 0; i < Dictionary.length; i += 1) {
    if (hasSubString(Dictionary[i], String)) {
      return `The longest word is "${Dictionary[i]}"`
    }
  }
  
  return `There are no substrings for this Dictionary`
}

### test
let D = ['larry', 'gingerbreadmuffin', 'egg', 'bibles', 'love']
 let S = "biagedinsbgeerabredagfeafadsmdfufdfdfki ng"
 console.log(searchString(S,D))// "gingerbreadmuffin"