JQuery :: Validation For Dynamic Field To Check The File Extension?

I am using jquery.validate.js for my validation. I need to validate some dynamic input fields. By using class now I am able to validate that. Here my problem is to validate for the file extension.

For static files I use as
file: {
required:true,
accept: "png|jpg",
},

How to write the accept validation for dynamically generated input fields. Below is my input field where the ID and name will change for every input field.

<input type="file" id="tval_1" name="tval_1" class="required accept" />