callback-sequence
Make a new callback to run callbacks in sequence or parallel.
Callbacks can be made async like gulp tasks.
Example
var thunkify = require('callback-sequence')
var Readable = require('stream').Readable
var gulp = require('gulp')
gulp.task('sequence', thunkify(
sync, async, promise, stream
))
gulp.task('parallel', thunkify(
[sync, async, promise, stream]
))
gulp.task('parallel-nested', thunkify(
// `async` and `promise` will be run in parallel
sync, [async, promise], stream
))
gulp.task('sequence-nested', thunkify(
// `async` and `promise` will be run in sequence
[sync, [async, promise], stream]
))
function sync() {
}
function async(cb) {
process.nextTick(cb)
}
function promise() {
return Promise.resolve()
}
function stream() {
var s = Readable()
s.push(null)
return s
}
API
var Runner = require('./lib/runner')
var runner = new Runner({ input: false, output: false })
exports = module.exports = runner.thunkify.bind(runner)
exports.run = exports.sequence = runner.sequence.bind(runner)
exports.parallel = runner.parallel.bind(runner)
exports.series = runner.series.bind(runner)
exports.Runner = Runner
Runner
var runner = Runner(opts)
Create a new runner instance.
opts
input
Specify whether to pass the results of the previous callback to the next as arguments.
Type: Boolean
Default: true
var Runner = require('callback-sequence').Runner
var runner = Runner({ input: true })
runner.thunkify(
function (a, b) {
// 3
return a + b
},
function (sum, next) {
process.nextTick(function () {
// 6
next(null, sum * 2)
})
},
function (product) {
return Promise.resolve().then(function () {
// 7
return product + 1
})
}
)(1, 2)
.then(function (res) {
// [7]
console.log(res)
})
output
Specify whether to deliver results.
Type: Boolean
Default: true
If false, the final results will always be [].
run
Specify a runner function to run each callback.
Type: Function, Object
Default: null
If Function, it receives a callback followed by a list of arguments,
and should return a promise to fetch the results (Array).
If Object, it is passed to
Runner of run-callback
to create a runner function.
cb = Runner.prototype.thunkify(...tasks)
Return a callback to run the specified tasks in the appearance order.
var runner = Runner()
runner.thunkify(
function (res) {
return res + 1
},
function (res) {
return Promise.resolve()
.then(function () {
return res + 1
})
},
function (res, next) {
process.nextTick(function () {
next(null, res - 1, res + 1)
})
}
)(1)
.then(function (res) {
// [ 2, 4 ]
console.log(res)
})
Runner.prototype.sequence(tasks)
Run tasks in sequence.
NOTE: directly nested array of tasks will be run with Runner.prototype.parallel.
var runner = Runner()
runner.sequence([
function () { console.log(1) },
[
function (cb) {
setTimeout(function() {
console.log(3)
cb()
}, 0)
},
function () {
return new Promise(function (resolve) {
process.nextTick(function () {
console.log(2)
resolve()
})
})
},
],
function () { console.log(4) },
]).then(function () {
console.log('DONE')
})
// 1
// 2
// 3
// 4
// DONE
Callbacks can be added dynamically:
var runner = Runner()
var count = 5
var tasks = []
var res = []
function task(next) {
process.nextTick(function () {
res.push(count)
if (--count > 0) {
tasks.push(task)
}
next()
})
}
runner.sequence(tasks).then(function () {
// [5, 4, 3, 2, 1]
console.log(res)
})
tasks.push(task)
Runner.prototype.parallel(tasks)
Run the specified tasks in parallel.
NOTE: directly nested array of tasks will be run with Runner.prototype.sequence.
var runner = Runner()
var res = []
runner.parallel([
function () { res.push(1) },
[
function () {
return Promise.resolve().then(function () {
res.push(4)
})
},
function () { res.push(5) },
],
function (cb) {
setTimeout(function() {
res.push(3)
cb()
}, 0)
},
function (cb) {
res.push(2)
cb()
},
])
.then(function () {
// [1, 2, 4, 5, 3]
console.log(res)
})
Runner.prototype.series(...tasks)
Run tasks in sequence.
However, while the results of sequence is that of the last task,
the results of series is an array containing all results of the tasks.
In addition, the results of the previous task will not be passed to the next as arguments.
NOTE: each element will be passed to Runner.prototype.sequence.
var runner = Runner()
runner.series(
function () {
console.log(1)
return 1
},
[
function () {
return Promise.resolve().then(function () {
console.log(4)
return 4
})
},
function (cb) {
setTimeout(function() {
console.log(3)
cb(null, 3)
}, 0)
},
function () {
console.log(5)
return 5
},
],
function (cb) {
console.log(2)
cb(null, 2)
}
)
.then(function (res) {
// 1
// 5
// 4
// 3
// 2
// [ [ 1 ], [ [ 4 ], [ 3 ], [ 5 ] ], [ 2 ] ]
console.log(res)
})
