JS | Add listener to every member of array/nodelist

var allAs = document.querySelectorAll('a');
allAs.forEach(
    function(el){
        el.addEventListener(
            "mousedown",
            function(){
                dataLayer.push({
                    'event' : 'gtm_link_click',
                    'eventAction' : this.innerText.toLowerCase(),
                    'eventLabel' : this.getAttribute('href').toLowerCase()
                });
                this.removeAttribute('href'); // for testing only so we don't follow links
            });
});