Roll Your own Look Up (SF)

//page
function Buyer_Prospect__c(u, rec){
    this.Id = rec
    this.Responsible_Broker__c = u
}
Visualforce.remoting.Manager.invokeAction(
    '{!$RemoteAction.BuyerProspectList_ext.getUsers}',
    (res, err) => {
        if(err.status){

            const contain = document.createElement('div')

            let select = `<select onchange="saveBpUser(e)">`
            select += `<option value="null">--None--</option>`
            let opts = res.map(x => select += `<option value="${x.Id}">${x.Name}</option>`);
            select += '</select>'

            contain.innerHTML = select
            select = contain.childNodes[0]

            const saveBpUser = (e) => {
                console.log(`This was changed ${e.target.value} for record ${e.target.parentElement.dataset.id}`)
                Visualforce.remoting.Manager.invokeAction(
                    '{!$RemoteAction.BuyerProspectList_ext.saveBpUser}',
                    new  Buyer_Prospect__c(e.target.value, e.target.parentElement.dataset.id),
                    (r, e) => e.status ? console.log(r) : console.error(e)
                )
            }

            const brokers = Array.from(document.getElementsByClassName('broker'))
            brokers.map(x => {

                const newSelect = select.cloneNode(true);
                newSelect.onchange = saveBpUser
                if(x.innerHTML){
                    newSelect.value = x.innerHTML
                    x.parentElement.replaceChild(newSelect, x)
                }
                else {
                    x.parentElement.replaceChild(newSelect, x)
                }
            })
        }
        else {
            console.error(err.message);
        }
    }
);

//controller
@remoteAction
 public static List<User> getUsers(){
     return [SELECT Id, Name FROM User WHERE isActive = true];
 }
 @remoteAction
 public static String saveBpUser(Buyer_Prospect__c bp){
    update bp;
    return 'Updated BP w user';
 }