Using external data resources

Reading resources via HTTP

There are different ways to load a resource. The method that is compatible with most browsers is XMLHttpRequest:

Note, however, that this method does not work for accessing an HTML file via file:// as detailed in a separate article.

You can use additional events of XMLHttpRequest such as error and progress.

Connection error reporting

The error event is called if there is a networking error, for example a connection loss during loading. Note that a Not found HTTP response is not handled by the error event. Instead, it must be handled manually using the request status as shown above in the load event listener.

Progress reporting

Progress events allow you to observe the loading process, which is interesting for large resources and slow network connections.

Writing resources via HTTP

The following example uses a HTTP PUT request to create/change data on disk. As this is a security risk, Kontrast HTTP server blocks PUT requests by default (and most HTTP servers block them in general). Please refer to the Kontrast HTTP server documentation for details on how to configure Kontrast HTTP server to allow PUT requests for certain directories.

Large binary data sets (such as typed arrays, e.g. Float64Array) are best written as a Blob.