How do I edit PHP variable with JavaScript/jQuery?

Question

I want to update a PHP variable $LinkOpen based on the current state of a checkbox element .avflipswitch.

Based on the .avflipswitch<

Answer 1

What you are trying is not possible in php, but very easy with jquery:

$('.avflipswitch').on("change", function (e){ 
    if(this.checked){
     $('a').attr("target","_self")
    }
    else{
     $('a').attr("target","_blank")
    }
});