Get the percentage of similar words between two texts. This function returns a score from 0 to 100 and an array of words in common between the two.

similarity.js

function similarity(text1, text2) {
    text1 = text1.split(/\s+/);
    text2 = text2.split(/\s+/);
    let wordsInCommon = [];
    let similarWordCount = 0;
    for (var i = 0; i < text1.length; i++) {
        let word = text1[i];
        if (text2.includes(word)) {
            similarWordCount++;
            if (!wordsInCommon.includes(word)) {
                wordsInCommon.push(word);
            }
        }
    }
    for (var i = 0; i < text2.length; i++) {
        let word = text2[i];
        if (text1.includes(word)) {
            similarWordCount++;
            if (!wordsInCommon.includes(word)) {
                wordsInCommon.push(word);
            }
        }
    }
    return {
        score: Math.floor(similarWordCount / (text1.length + text2.length) * 100),
        wordsInCommon
    }
}