beforeSend (Data Interception and Modification)¶

The RUM SDK executes the beforeSend method before sending each piece of data. By customizing the implementation of this method, you can achieve the following operations:

• Modify parts of the data
• Intercept the data being sent

beforeSend provides two parameters:

function beforeSend(event, context)

event is the object generated by the SDK that collects various metric data. For specific information about context, refer to the table below:

Modifying Parts of the Data¶

window.DATAFLUX_RUM &&
    window.DATAFLUX_RUM.init({
        ...,
        beforeSend: (event, context) => {
            if (event.type === 'resource' && event.resource.type === 'fetch') {
                // Add the response headers of the request to the original data
                event.context = {...event.context, responseHeaders: context.response.headers}
            }
        },
        ...
    });

The fields that the SDK allows to modify are listed in the table below:

Intercepting Data to be Sent¶

You can intercept unwanted data by returning true or false from the beforeSend method.

• true indicates this piece of data should be reported.
• false indicates this piece of data should be ignored and not reported.

window.DATAFLUX_RUM &&
    window.DATAFLUX_RUM.init({
        ...,
        beforeSend: (event) => {
            if (shouldDiscard(event)) {
                return false
            } else {
                return true
            }
            ...
        },
        ...
    });