​x
 
<!DOCTYPE html>
<html>
<body>
​
<iframe id="myframe" src="/demo/htmldom/iframe.html"></iframe>
​
<p>单击该按钮可更改 iframe 中包含的文档的背景颜色。</p>
​
<p id="demo"></p>
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<button onclick="myFunction()">试一试</button>
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<script>
function myFunction() {
  var x = document.getElementById("myframe");
  var y = (x.contentWindow || x.contentDocument);
  if (y.document)y = y.document;
  y.body.style.backgroundColor = "red";
}
</script>
​
</body>
</html>
​