idf2.js

function inverseDocumentFrequency(documents){
    // calculates the inverse document frequency of every sentence
    const words_without_stopwords = prettify(documents);
    const sentences = documents.split(".")
    sentences[0] = sentences[0].substring(146);
    const lengthOfDocuments = sentences.length;

    const WordCountDocuments = countWords(words_without_stopwords);
    // calculate TF values of all documents

    const unique_words_set = uniqueWords(words_without_stopwords);

    let IDFVals = {};

    for (let i = 0; i <= unique_words_set.length - 1; i++){
        IDFVals[unique_words_set[i]] = Math.log10(lengthOfDocuments / WordCountDocuments[unique_words_set[i]]);
    }