real-vision-code-test.js

// ASSUMPTION
// text files will be placed in the same directory as the program file

// Question
// is the word case-insensitive? not specified in the problem statement
// so in the code below, I take care of each words as case-insensitive e.g.) so & So are the same words

// HOW TO RUN PROGRAM
// node <file_name> <sampleFile> <commonFile>
// for example, node test.js alice_in_wonderland.txt 1-1000.txt

const fs = require('fs');

const [,,sampleFile, commonFile] = process.argv;

const readFileAsync = async function({fileName, delimiter}) {
    return new Promise(function(resolve, reject) {
        fs.readFile(fileName, 'utf-8', function(err, data){
            if (err)
                reject(err);
            else
                resolve(data.split(delimiter));
        });
    });
};

const files = [
    {
        fileName: sampleFile,
        delimiter: ' ',
    },
    {
        fileName: commonFile,
        delimiter: '\n',
    }
];

(async() => {
    const [sampleFileData, commonFileData] = await Promise.all(files.map((file) => readFileAsync(file)));

    // get rid of the carriage return
    const cleanCommonData = commonFileData.map((word) => word.slice(0, -1));

    // freqMap
    const freqMap = new Map();
    for(const sampleWord of sampleFileData) {
        if (sampleWord) {
            // currently accept the word combination of
            // alphanum + [._%-'`] + alphanum
            // we could add more special cases
            const regexTester = new RegExp(/^([a-zA-Z0-9]+[a-zA-Z0-9._%-'`]+[a-zA-Z0-9]+)?$/);
            // not include in the commonData (case-insensitive)
            if (regexTester.test(sampleWord) && !cleanCommonData.includes(sampleWord.toLowerCase())) {
                freqMap.set(sampleWord, (freqMap.get(sampleWord) || 0) + 1);
            }

        }
    }
    // sort by freq in descending order
    const sortedFreqMap = new Map([...freqMap.entries()].sort((a, b) => b[1] - a[1]));
    
    console.log(`Count  Word`);
    console.log(`=== ====`);
    for (const [word, freq] of sortedFreqMap) {
        console.log(`${freq}  ${word}`);
    }

})();