how to check for a condition in the .then() function of the Promise

Question

I'm trying to check if the result from an api calls returns anything and based on that do some other actions but the following code always go through the process_result() function even though the result is an empty object, can anyone see what I'm doing wrong,

RemoteApi.api_request(server, method, url, data)
    .then(result => {
        debug("result from API request: ", result)
        debug("data from API request: ", data)
        if (result !== {}) {
            debug("in process result now")
            process_result(result, label, model, dispatchOptions)
                .then(body => {
                    onSuccess(body)
                })
                .catch(error => {
                    onFailure(error)
                })
        } else {
            debug("outside process result now")
        }
    })
    .catch(error => onFailure(error))

You need a different check; *every* Object, no matter what kind, will be `!== {}` (not identical to that new one). — , Feb 27 '19 at 08:20

score 0 · Answer 1 · answered Feb 27 '19 at 08:29

Generally remote requests that return a 2XX result will enter your then() function. Once there its plain old JavaScript.

If you want to ensure the result is an object you can check the type:

if (typeof result === 'object') {
  // success
}

If you don't care for the result contents but you want to check if data is there, you could just check if its truthy:

if (result) {
  // success
}

The remote result could never be an identical instance of {} so your results process will always be truthy.

how to check for a condition in the .then() function of the Promise

1 Answers1