JSFiddle - React, Tailwind, and code Playground

HTML

<a class="button call" href="#" data-number="6135555556">Call pager</a>
<a class="button call" href="#" data-number="6135555555">Call cell</a>

JavaScript

var data = document.getElementsByClassName("call");
var numbers = [];
for (var i = 0; i < data.length; i++) {
     data[i].onclick = getNumber;
}

function getNumber(){
    numbers.push(this.dataset['number']);
	alert(this.dataset['number']);
}