Handling the Remote Response in JavaScript Remoting

The Callback Function receives 2 parameters

• Event object: represents the status of the remote call

•   event.status : true on success, false on error.
•   event.type :  type of the response: rpc for a successful call, exception if the remote method threw an exception, and so on.
•   event.message : contains any error message that is returned.
•   event.where : contains the Apex stack trace, if one was generated by the remote method.

• Result object: represents result returned by the remote Apex method

• Apex primitive data types returned by result—such as strings or numbers—are converted to their JavaScript equivalents.
• Apex objects that are returned are converted to JavaScript objects,
• Collections are converted to a JavaScript array.
• Keep in mind that JavaScript is case-sensitive, so id, Id, and ID are considered different fields.

Points to remember

•   The remote method call executes synchronously, but it doesn’t wait for the response to return.
•   When the response returns, the callback function handles it asynchronously.
•   By default, the response of the remote call must return within 30 seconds, after which the call will time out. If your request needs longer to complete, configure a longer timeout, up to 120 seconds.
•   The response of the remote call has a maximum size of 15 MB.