首页javascriptjsonJavascript Data Type - 如何将未定义的变量更改为空字符串...

Javascript Data Type - 如何将未定义的变量更改为空字符串...

我们想知道如何将未定义的变量更改为空字符串。...

<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'>
var s = '{ "name": "John", "family": "Resig" }';
var o = JSON.parse(s);
document.writeln(o.name); // John
document.writeln('<br/>');
document.writeln(o.family); // Resig

</script>
</head>
<body>
</body>
</html>