@formspark/formtrack/src/appendOrUpdateInput.ts

Automatically inject UTM parameters into your HTML form submissions

const appendOrUpdateInput = ({
  formElement,
  id,
  name,
  value,
}: {
  formElement: HTMLElement;
  id: string;
  name: string;
  value: string;
}) => {
  let input = document.getElementById(id);
  if (!input) {
    const newInput = document.createElement("input");
    newInput.setAttribute("type", "hidden");
    newInput.setAttribute("id", id);
    newInput.setAttribute("name", name);
    formElement.appendChild(newInput);
    input = newInput;
  }
  input.setAttribute("value", value);
};

export default appendOrUpdateInput;