001 Load Valid Words

001 Load Valid Words.js

// Predefined constants
const wordFilePath = "resources/google-10000-english-usa-no-swears.txt";
const minWordLength = 3;
const maxWordLength = 6;

// Cached global variables
var words = []

/**
 * Loads a list of words from the file at `wordFilePath`, which should contain
 * a list of newline-delimited words. Uses lineReader to do this in a buffered
 * and asynchronous manner.
 *      callback - A function that gets called when the file is done being read
 *                 (callback should not take any parameters)
 */
function loadValidWords(callback) {
    
    // If we already loaded the words, just return the already-loaded words!
    if (words.length > 0) {
        return words;
    }
    
    // Otherwise, startup the buffered reader
    var instance = lineReader.createInterface({
        input: fs.createReadStream(wordFilePath)
    });

    // If a line is encountered, add it to our list if it satisfies the length
    // constraints
    instance.on('line', function (line) {
        var wordLength = line.length;
        if (wordLength >= minWordLength && wordLength <= maxWordLength)
            words.push(line);
    });
    
    // Once finished, call the callback
    instance.on('close', function (line) {
        callback();
    });
    
}