Copyright © tutorialspoint.com
This method returns true if obj is of type undefined, false otherwise.
Object.isUndefined(obj); |
<html> <head> <title>Prototype examples</title> <script type="text/javascript" src="/javascript/prototype.js"> </script> <script> function showResult(){ alert( "test 1: " + Object.isUndefined() ); alert( "test 2: " + Object.isUndefined(undefined) ); alert( "test 3: " + Object.isUndefined(null) ); alert( "test 4: " + Object.isUndefined(0) ); } </script> </head> <body> <p>Click the button to see the result.</p> <br /> <br /> <input type="button" value="Result" onclick="showResult();"/> </body> </html> |
To understand it in better way you can Try it yourself.
Copyright © tutorialspoint.com