SFRA / Server-side JS / Tutorial: How to cache responses

How to cache responses

The caching of responses is controlled by setting the expiration time at the response object. While it is possible to set the caching behavior using the tag in ISML templates, this is not considered best practice. In particular, if you intend to use other templating languages besides ISML, such as velocity, it makes more sense to set the caching in the controller.

By default, responses are not cached. Caching is only supported for buffered responses for HTTP GET requests. Streamed responses cannot be cached.

If the expiration time is set multiple times at the response, the minimum value is used.

Absolute expiration time

For setting an absolute expiration time, a new date object for the time can be created and set at the response.

/**
 * The function that handles the request.
 */
function world(){
    // new Date(year, month, day, hours, minutes, seconds, milliseconds)
    var expires = new Date(2100, 4, 1, 12, 0, 0, 0);

    response.setExpires(expires);
    response.getWriter().print("Hello World!")
}

exports.World = require('~/cartridge/scripts/guard').ensure(['get'], world);

Cache daily until 3 am in the morning. This is today if executed before 3am, or tomorrow if executed after 3 am.

    var Calendar = require('dw/util/Calendar');

    var now = new Calendar();
    var then = new Calendar();
    then.set(Calendar.HOUR_OF_DAY, 3);
    if (then.before(now))
    {
        then.add(Calendar.DATE, 1);
    }

    response.setExpires(then);

Relative expiration time

For relative expiration, the time can be calculated by adding the caching period to the current time. Using a calendar object can make the calculations easier.

Caching for 30 minutes from now on, using a calendar:

    var Calendar = require('dw/util/Calendar');

    var c = new Calendar();
    c.add(Calendar.Minute, 30);

    response.setExpires(c.getTime()); // c.getTime() returns a JavaScript Date

Caching for 30 minutes from now on, without calendar:

    response.setExpires(Date.now() + 30 * 60 * 1000);

Disable caching

Caching can be disabled by simply setting an expiration time of 0.

    response.setExpires(0);

That's how you cache responses!