Resolving a setTimeout inside API endpoint
I need to add a delay to an API call so I'm using setTimeout . After 2 seconds on success, I need to return res.status(200).json(response) .
exports.someEndpoint = function(req, res) {
return request.post({
url: //etc
})
.then(function(response) {
return new Promise(function(resolve, reject) {
setTimeout(function() {
// is this right?
resolve(
res.status(200).json(response);
);
}, 2000);
});
});
};
My question is: do I need to call resolve inside the setTimeout ? Or can I just completely omit it?
Your code is equivalent to:
exports.someEndpoint = function(req, res) {
return request.post({
url: //etc
})
.then(function(response) {
setTimeout(function() {
res.status(200).json(response);
}, 2000);
});
};
But only because it is an Express route handler that's not expected to return anything in general or a promise in particular.
On the other hand your code:
exports.someEndpoint = function(req, res) {
return request.post({
url: //etc
})
.then(function(response) {
return new Promise(function(resolve, reject) {
setTimeout(function() {
// is this right?
resolve(
res.status(200).json(response);
);
}, 2000);
});
});
};
could be called as:
yourModule.someEndpoint(req, res).then(function () {
// code to run after the timeout
});
which wouldn't be possible in the shorter version.
Do I need to call resolve inside the setTimeout?
It depends on what is going to happen with exports.someEndpoint , but usually yes - you would want to return a Promise that has completed all async operations in it's fulfilled state.
For example if your express handler is being captured by a function that expects a promise, then the flow will continue, before you have returned a response to your user.
If you don't care about promises in your request handler, then you can also not return request.post({ and just return nothing.
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