Parameter Pass-Through

passparams.js

// Catch the incoming params
const incomingQueryString = window.location.search.substring(1); // drops ? from the front;

// Capture all of the link clicks
document.addEventListener(`click`, (e) => {
  // if it's an <a> link
  if (e.target.closest(`a`) && incomingQueryString.length > 0) {
    e.preventDefault();
    // if it already has params, combine them, if not, add the new ones
    window.location.href =
      e.target.href +
      (e.target.href.indexOf("?") === -1 ? "?" : "&") +
      incomingQueryString;
  }
});

This just catches all of the parameters in the URL and appends them to the links on the page.

Particularly useful when you want to add a campaign parameter to an advertisement link that goes to a sales page and you want that parameter to continue through to the order form without having to manually add it to the sales page.