Ifram & ASP.net

i am using following code for trying to send a value from iframe to webpage and want to submit automatically  using java script, but getting an following error,
"Uncaught DOMException: Failed to read the 'contentDocument' property from 'HTMLIFrameElement': Blocked a frame with origin "http://localhost:53182" from accessing a cross-origin frame."

My code is

      function load() {

          alert("hh");
           // get the iframe in my documnet
    var iframe = document.getElementById("myframe");
    // get the window associated with that iframe
    var iWindow = iframe.contentWindow;

    // wait for the window to load before accessing the content
  
        var doc = iframe.contentDocument || iframe.contentWindow.document;

        // find the target in the iframe content
        var target = doc.getElementById("txtLrNo");
        target.innerHTML = "Found It!";
      }

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