将图标标签添加到按钮中的innerHTML

Question

I'm trying to create a function in JavaScript, which on the button click changes class and adds a green checkmark, which is the icon tag in html.

I tried this:

function markerValg(btnID) {
    knap = document.getElementById(btnID);
    knap.classList.remove("unselected");
    knap.classList.add("selected");
    document.getElementById(btnID).innerHTML = += <i class="fa fa-check ikon"></i>

Answer 1

将最后一行代码更改为

document.getElementById('test').innerHTML = '<i class="fa fa-check ikon"></i>';

<button id='test'>Check</button>