Implementing caching in an API function Last updated: 19. Mar 2025

This function implements caching for an API endpoint by checking the 'If-Modified-Since' header and returning a 304 status if the content has not been modified.

Example

Code API/Test.js

// Format the site's last modified date
let formattedSiteModifiedDate = docly.format(request.sitemodified, "R");
docly.setHeader("Last-Modified", formattedSiteModifiedDate);

// Retrieve the 'If-Modified-Since' header from the request
let ifModifiedSinceHeader = docly.getHeader("If-Modified-Since");
if (ifModifiedSinceHeader) {
    // Convert the 'If-Modified-Since' header to a Date object
    let ifModifiedSinceDate = new Date(ifModifiedSinceHeader);

    // Calculate the difference between the 'If-Modified-Since' date and the site's last modified date
    let dateDifference = docly.dateDiff(ifModifiedSinceDate, request.sitemodified);
    
    // If the difference in seconds is less than 1, set the result code to 304 (Not Modified)
    if (dateDifference.TotalSeconds < 1) {
        let formattedSiteModifiedDate = docly.format(request.sitemodified, "R");
        docly.setHeader("Last-Modified", formattedSiteModifiedDate);
        return docly.setResultCode(304);
    }
}

// Return an embedded file?
// docly.downloadEmbeded(file, embeddedId, "filename.pdf");

// Return what ever object you want here (not cached)
return {
    "ifModified": ifModifiedSinceHeader,
    "siteModified": formattedSiteModifiedDate,
    "diff": dateDifference.TotalSeconds
};