Buenas prácticas JS

index.html

<button id="btn">Like</button>
<span id="mostrar">0</span>

Like-Incremente-js.markdown

LIKE INCREMENT

A Pen by Yerlin Matu on CodePen.

License.

script.js

let btn = document.querySelector('#btn'),
    span = document.querySelector('#mostrar'),
    like = 0;

function addLike () {
    return ++like;
}

btn.addEventListener('click', () =>{
    span.innerHTML = addLike();
    
})

Like++