Promise patterns

[anandkumarpatel]

Let us discuss our new coding patterns now that we moved everything to promises:

Method 1 Linear program w/ comments

Promise.try(() {
  // JSDoc
  ... code ...
})
.then(doSomething1 () {
  // JSDoc
  ... code ...
})
.then(doSomething2 () {
  // JSDoc
  ... code ...
})
.then(doSomething3 () {
  // JSDoc
  ... code ...
})

Pro: looks linear
Cons: unit testing is harder, requires more setup

Method 2 Functional

Promise.try(() {
 return fn1()
})
.then(() {
  return fn2()
})
.then(() {
 return fn3()
})
.then(() {
 return fn4()
})
// JSDoc
fn1 = {
  ... code ...
}
// JSDoc
fn2 = {
  ... code ...
}
// JSDoc
fn3 = {
  ... code ...
}
// JSDoc
fn4 = {
  ... code ...
}

Pro: functions are broken up into smaller components. Each function can have proper unit tests and docs
Con: have to look at different areas on the page to understand full function.

Any other methods people prefer & which do you like the most?

[podviaznikov]

Another solution is to add names to anonymous functions.

Promise.try(() {
  return fn1()
})
.then(doSomething1 () {
  return fn2()
})
.then(doSomething2 () {
  return fn3()
})
.then(doSomething3 () {
  return fn4()
})

That way you still can collapse all functions and see "the big picture" instead of seeing this:

and reading function implementation in order to understand what function does and what it returns

[thejsj]

Code folding is fot n00bs, but I like @podviaznikov's suggestion. I think name methods work well. I do like keep the linear structure of it.

Also, I think we could add some JSDoc between these methods:

Promise.try(() {
  return fn1()
})
/**
 * @param {String} name
 * @returns {Promise}
 * @resolves {String}
 */
.then(doSomething1 (name) {
  return fn2()
})
/**
 * @param {String} name
 * @returns {Promise}
 * @resolves {String}
 */
.then(doSomething2 (name) {
  return fn3()
})\/**
 * @param {String} name
 * @returns {Promise}
 * @resolves {String}
 */
.then(doSomething3 (name) {
  return fn4()
})

[podviaznikov]

haha, code folding is workaround in order to achieve same feature as Method 2 provides. I'd rather have Method 2, but code folding with Method 3 would work for me too.