Securize dynamically target blank links

securize_blank_links.js

function setRelAttribute() {
    const elems = document.body.getElementsByTagName('a');
    for (let i = 0; i < elems.length; i++) {
        const elem = elems[i];
        elem.setAttribute('rel', 'noopener noreferrer nofollow');
    }
}

const ready = (callback) => {
    if (document.readyState !== 'loading') callback();
    else document.addEventListener('DOMContentLoaded', callback);
}

ready(() => { 
    document.body.addEventListener('DOMSubtreeModified', function () {
        setRelAttribute();
    }, false);
});