从iframe访问某些值并在父页面Javascript中使用它

Question

Inside my iframe i have a dial that spits out angle when the needle moves. Instead of getting both dial and needle both inside frame, is it possible to show the angle value somewhere else in my parent page outside the iframe. This is the code i have.

function showIframeContent(id) {
  var iframe = document.getElementById(id);
    try {
      var doc = (iframe.contentDocument)? window.frames[clkwise1].document.getElementId("demo").value;
      alert(doc.body.innerHTML);
    }
    catch(e) {
       alert(e.message);
    }
  return false;
}

Answer 1

The standard and cross-browser way to access the content of an iframe is:

iframe.contentWindow.document

I would expect this to work in your case:

document.getElementById("clkwise1").contentWindow.document.getElementById("demo").value

(I'd need to see the page itself to confirm it - for example I assume "demo" is an input element. Also, note your typo in getElementById)

Live demo: http://jsfiddle.net/ZWC6v/