示例1：子窗口是新打开的窗口
父窗口:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" " https://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns=" https://www.w3.org/1999/xhtml">
<head>
<title>parent</title>
<script type="text/javascript">
var parentPara='parent';
function parentFunction() {
alert(parentPara);
}
</script>
</head>
<body>
<button onclick="parentFunction()">显示变量值</button>
<button onclick="window.open('child.html')">打开新窗口</button>
</body>
</html><!DOCTYPE html PUBL
