product page: purchase validation

I'd like to validate (via AJAX) that a user is permitted to purchase a product and if not, disable the "Add to cart" button in the product page and show some text explaining why they are not allowed to purchase the item.

I do not want to put products behind a Wix membership or password as I want prospective clients to see that the products exist and generate interest even if they aren't currently eligible to purchase.

If only I had access to the DOM...

if (!eligible(contact) {

// disable the addToCart button

document.querySelectorAll(`button[class*="AddToCart"], button[class^=" AddToCart"`)[0].disabled = true

// reduce the opacity of the AddToCart button

document.querySelectorAll(`button[class*="AddToCart"], button[class^=" AddToCart"`)[0].setAttribute('style', 'opacity:0.2')

// add subtext below the button explaining why

let warn = document.createElement('div')

warn.setAttribute('style', 'text-align:center;')

let warnSmall = document.createElement('small')

let warnText = document.createTextNode('Must be a member')

warn.appendChild(warnSmall)

warnSmall.appendChild(warnText)

document.querySelectorAll(`button[class*="AddToCart"], button[class^=" AddToCart"`)[0].parentElement.appendChild(warn)

}