To resolve the issue where the first item in a mobile dropdown isn’t selectable using JavaScript, follow these steps:

1. Check HTML Structure: Ensure all <option> elements are correctly nested within the <select> element and have valid value attributes.

2. Inspect CSS Styling: Remove any styles that might hide or disable the first option. Look for conflicting z-index values or positioning issues in your CSS.

3. Review JavaScript Code: Check for event listeners on the dropdown that may interfere with default selection behavior. Ensure no code intentionally prevents selecting the first item.

4. Test Touch Interactions: Verify that touch events are handled correctly, as some mobile browsers might have specific behaviors regarding focus and blur.

5. Use Browser Developer Tools: Debug using tools like Chrome DevTools to inspect event handling on the dropdown items. Look for any discrepancies when interacting with the first option.

6. Implement a Workaround: If necessary, use JavaScript to programmatically trigger focus events on the dropdown to ensure all options are selectable.

By systematically checking each aspect—HTML, CSS, JavaScript, and touch interactions—you can identify and fix the root cause of the issue.