i want to modify a href here.
Please do not show us an image. We can not edit or test an image.
But, first, you must understand that PHP code is SERVER-SIDE-ONLY. And, Javascript is CLIENT-SIDE-ONLY. ( client side means in the browser! )
Therefore, you can NOT use Javascript to alter PHP code. PHP code is executed on the server BEFORE it is sent into the browser. You can not change it. That is why it is secure and encrypted code can not be hacked that way!
Your system can not work the way you wish it to!