How to Build a Five-Letter Word Filter Using Plain JavaScript

A tutorial on DEV Community walks developers through creating a five-letter word filter using vanilla JavaScript, requiring no external libraries or APIs. The filter supports three conditions: a positional pattern using question marks for unknown letters, required letters that must appear somewhere in the word, and excluded letters that must not appear at all. Each condition is handled by a dedicated function, and all three are combined into a single filterWords utility that normalizes and validates user input before processing. A regex check ensures the pattern is exactly five characters, and a Set is used to avoid redundant letter checks. The tutorial uses a small sample word list to demonstrate the logic, noting that a production tool would rely on a larger, validated dataset.