Is there a way to make this work ?
style.left = "10vmax + 10px"
With calc function in css, use the style.left property on the element.
document.querySelector('.item').style.left = 'calc(10vmax + 10px)'.item {
background: red;
height: 100px;
width: 100px;
position: relative;
}<div class="item"></div>