how to check whether web widget is loaded or not ?

Hello Sparrowtest,

To assess the loading capabilities of the Zendesk web widget, we would kindly suggest using the Google Chrome Developer Console. Specifically, you might find the Network tab particularly useful. In this tab, you can verify the status code.
 
A status code of 200 typically indicates a successful operation. I would also recommend paying special attention to the 'Initiator', particularly 'snippet.js'.
 
I've included a screenshot below for your reference, taken from my own test account:

Should there be any error codes, they would be highlighted in red for easy identification.

Hope it helps