<div class="container">
<span>1</span>
<span>2</span>
<span>3</span>
<span>4</span>
<span>5</span>
<a href="#" class="btn btn-outline-primary">按鈕</a>
</div>$(document).ready(function(){
let el = document.querySelector('a');
el.setAttribute('href', 'https://www.google.com/');
console.log(el.getAttribute('href'));
})