Run PHP in Javascript [duplicate]

let lvlcount = 0;

  function loadmore(){

    if (lvlcount == 0){
      document.getElementById("d").innerHTML = lvlcount;
      lvlcount =+ 1;
    }else if (lvlcount == 1){
      document.getElementById("d").innerHTML = '<?php require("./parts/levels/lvl-456.php"); ?>';
      lvlcount += 2;
    }
  }

How can I run PHP Code in Javascript? I want to add Code when someone clicks on the button, the Code is saved in an PHP File.