Javascript easy one line solution
Complexity\n- Time complexity: O(n*m)\n Add your time complexity here, e.g. O(n) \n\n- Space complexity: O(n)\n Add your space complexity here, e.g. O(n) \n\n# 
# Complexity\n- Time complexity: O(n*m)\n<!-- Add your time complexity here, e.g. $$O(n)$$ -->\n\n- Space complexity: O(n)\n<!-- Add your space complexity here, e.g. $$O(n)$$ -->\n\n# Code\n```\n/**\n * @param {string[]} words\n * @param {string} s\n * @return {number}\n */\nvar countPrefixes = function (words, s) {\n  return words.filter((item) => s.startsWith(item)).length\n}\n```
['JavaScript']