How can I create a dropdown menu in the hero section of a Webflow website that is preselected based on the ad that brought the user there?

To create a preselected dropdown menu in the hero section of your Webflow website, you will need to utilize Webflow's built-in form element and custom code functionality. Here's a step-by-step guide on how to achieve this:

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Step 1: Set up a dropdown menu

- Add a form element to your hero section by dragging and dropping the "Form" component from the Add panel.

- Inside the form element, drag and drop a "Select field" (dropdown) from the Add panel.

- Double-click the select field to open its settings panel on the right.

- Expand the "Option 1" section and provide a label and value for the option. Repeat this for any additional options you want to include in the dropdown.

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Step 2: Add custom code to preselect the dropdown option

- Select the hero section and go to the Settings panel on the right.

- Scroll down to the "Custom Code" section and click the "Before </body>" tab.

- In the custom code field, you can write JavaScript logic to preselect the dropdown option based on the ad that brought the user there. 

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Here's an example code snippet assuming you have a URL parameter `ad` that holds the value of the ad:

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```javascript

<script>

  // Get the value of the 'ad' parameter from the URL

  const urlParams = new URLSearchParams(window.location.search);

  const ad = urlParams.get('ad');

​

  // Select the dropdown element using its class or ID

  const dropdownElement = document.querySelector('.your-dropdown-class');

​

  // Loop through each option in the dropdown and set the selected option

  for (let i = 0; i < dropdownElement.options.length; i++) {

    const option = dropdownElement.options[i];

    if (option.value === ad) {

      option.selected = true;

      break;

    }

  }

</script>

```

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Replace `.your-dropdown-class` with the actual class or ID of your dropdown element, and make sure to adjust the URL parameter name and the comparison logic (`option.value === ad`) based on how your ad URL parameter is structured.

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Step 3: Publish and test

- Once you have added the custom code, you can publish the site to see the dropdown preselected based on the ad parameter in the URL.

- Test it by opening different ad URLs and verifying if the appropriate dropdown option is preselected.

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By combining the use of Webflow's form element with custom code, you can dynamically preselect a dropdown option based on the ad that brought the user to your website.