Billionaire-to-oligarch browser extension

replace.js

const re = /billionaire/gi;

const replacer = (match) => {
    if(match === "Billionaire") {
        return "Oligarch";
    }
    else if(match === "BILLIONAIRE") {
        return "OLIGARCH";
    }
    else {
        return "oligarch";
    }
}

const observer = new MutationObserver(mutationList => {
    mutationList.forEach(mutation => {
        if(mutation.type === "characterData") {
            replaceText(mutation.target);
        }
        else if(mutation.type === "childList") {
            processNodes(mutation.target);
        }
    });
});

observer.observe(document.body, {
    subtree: true,
    characterData: true,
    childList: true
});

const replaceText = node => {
    if(re.test(node.textContent)) {
        node.textContent = node.textContent.replaceAll(re, replacer);
    }
};

const processNodes = rootNode => {
    const nodeIterator = document.createNodeIterator(rootNode, NodeFilter.SHOW_TEXT
    );

    while(currentNode = nodeIterator.nextNode()) {
        replaceText(currentNode);
    }
};

processNodes(document.body);