# postreqs: make http post requests via javascript

if i have a web form such as a login page (username+password) or a comment box then i try to use the following pattern:

• the user enters their data and presses the login, post, etc button.
• the webpage makes a http post request for the action in javascript within the page.
• the webpage shows some indication that the request is in flight. such immediate feedback is important to make the page feel snappy.
• if it errors out then the error is presented to the user on the same page. they can easily retry because there's no data lost. no need to retype the password since the page never navigated away.
• on success the page is reloaded or redirected to the target via a standard http get request. no more "confirm form resubmission" prompts as the user navigates back and forth in their history. or if possible, updating without a refresh at all is also nice.

contrast this to the traditional approach where the redirect/reload always happens on form submit. i think the in-page approach has a much better user interface properties than reloading the whole page with the result of the http post request. and i believe the above is much easier to implement than the traditional approach. the http post endpoints can remain pure api endpoints that a few lines of javascript can handle.

furthermore errors like overload are much easier to handle gracefully. on a traditional page the user must continuously retry and hope for the best. and this often results in duplicate posts. the javascript approach can automatically retry with some fancy retry algorithms. all while keeping the web page responsive and the user well informed about the status.

the downside of this approach is that it requires javascript. that's fair game nowadays if done reasonably. i think it's reasonable to avoid catering to the lowest common denominator. rather make the whole website and its content also accessible via an api so that it's easy for the users to write custom frontends. rely solely on the same api for the official frontend. this ensures that if you ever go overboard, users should be able to respond by writing a better frontend. make replacing your site easy rather than making it artificially important. that's how you can signal trust and its a form of a long term commitment (@/commitments) to be a good guardian of whatever data the users trust you with.

(speaking of responsive ui, here's a good overview what latencies we should be targeting: https://www.nngroup.com/articles/response-times-3-important-limits/. ideally a site's response is so fast that the user doesn't even notice step 3's feedback at all.)

published on 2024-03-09

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