function add_asset() {
    let serial = document.getElementById("add-asset-serial");
    let tag = document.getElementById("add-asset-tag");
    let category = document.getElementById("add-asset-category");
    let model = document.getElementById("add-asset-model");

    if (tag.value == "") {
        tag = null;
    } else {
        tag = tag.value;
        document.getElementById("add-asset-tag").value = "";
    }
    if (serial.value == "") {
        alert('Serial field cannot be empty!')
        return;
    } else {
        serial = serial.value;
        document.getElementById("add-asset-serial").value = "";
    }
    if (category.value == "N/A") {
        category = null;
    } else {
        category = category.value;
        document.getElementById("add-asset-category").value = "N/A";
    }
    if (model.value == "N/A") {
        model = null;
    } else {
        model = model.value;
        document.getElementById("add-asset-model").value = "N/A";
    }

    console.log(serial,tag,category,model);

}