Javascript parameters always being treated as an object

I have a simple method along with a simple button click and I’m unable to get the string from the passed in button. For some reason, the object is always a string and I’m not sure why. This is for a MVC App using Telerik. In the below grid, n the button click you’ll see I’m trying to pass in rebind as a string, however, this is always an object. How do I get the string?

<button onclick="bindGrid('rebind');"> Apply Filters</button>

const activeStatesOptions = document.getElementById("activeStates");
const daysOnMarketOptions = document.getElementById("daysOnMarket");
const prospectStatusOptions = document.getElementById("prospectStatus");

function additionalInfo(rebind) {
    if (daysOnMarketOptions.options.length == 0)
    {
        return {
            state: "",
            dom: "",
            status: "",
            rebind: ""
        }
    }
    alert(JSON.stringify(rebind));
    alert(rebind);
    return {
        state: activeStatesOptions.value,
        dom: daysOnMarketOptions.value,
        status: prospectStatusOptions.value,
        rebind: rebind
        //prospectStatusOptions.options[prospectStatusOptions.selectedIndex].value
    }
}