Getting value GET OR POST variable using JavaScript?

Question

How to get value of the get or post variable on page load using JavaScript?

Answer 1

When i had the issue i saved the value into a hidden input:

in html body:

... then put the hidden input on the page and write the value $fid with php echo

then in $(document).ready( function () {

    var postId=document.getElementById("fid").value;

so i got my hidden url parameter in php an js.