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 part of the data
• Intercept sending data

beforeSend provides two parameters:

function beforeSend(event, context)

event is generated by the SDK to collect various metric data objects. For context, refer to the following specific information:

Modify Part 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 information to the original data
                event.context = {...event.context, responseHeaders: context.response.headers}
            }
        },
        ...
    });

The fields allowed to be modified by the SDK are listed in the following table:

Intercept Sending Data¶

You can intercept some unnecessary data by returning true or false in the beforeSend method.

• true indicates that this piece of data needs to be reported
• false indicates that this piece of data should be ignored

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