set up form option as default in a drop down

问题:

I have created a driven database drop down menu on my website. It sends the selected value by the user to the database to be checked and returns a specific item.

Everything works perfectly now but I'm trying to pre select the first value so that the user will have the first option as default and can add it to cart directly and they also can choose a different size. So far, I tried 'selected' inside the option in the drop down but it doesn't do anything but displays the value when the page loads.

One last thing to mention, I'm using Ajax function to submit selected value and return result from the database.

回答1:

I can think of two ways for this.

1. When the page is requested, make a call to your DB in your server-side code to store that value beforehand.
2. Use javascript's onload event to select the value as a part of a client-side script. You can use this answer as reference.