how to get the value of textfield in variable on same page?

Do you mean the value of a textfield in javascript variable?

First of all, wrong forum.

If you mean the value of a form text field then you can access it with Javascript, look at some jQuery tutorials to help you understand how to use it.

Or you can have some PHP above everything in your page, set a variable with a default value of null. Send the form to the same page, if it has a value add it to the variable, if not continue as normal.

You could also reset the form action upon setting the variable.

My code is messy but the logic is there.