chainr
v0.2.0Chainr
Simple flow control library inspired by seq by substack and async by caolan.
The interface is quite similar but with a reduced function range.
Instead of using the this
property to assign a done-callback the traditional node way is used (a callback function as the last parameter).
Installation
npm install chainr
API
.seq(cb)
.seq(name, cb)
Functions registered via .seq
are executed in sequential order.
Each cb
gets a callback assigned which is used to signal the end of the callback execution.
If name is specified, the second argument sent to cb
goes to chain.var
.
example/seq.js
var chainr = require('../');
var chain = chainr();
chain
.seq('foo', function (cb) {
console.log('1');
setTimeout(cb.bind(null, null, 'bar'), 100);
})
.seq(function (cb) {
console.log('2');
setTimeout(cb, 100);
})
.seq(function (cb) {
console.log('3');
console.log(chain.vars);
});
Output:
1
2
3
{ foo: 'bar' }
.par(cb)
.par(name, cb)
Functions registered via .par
are executed in parallel.
Each cb
gets a callback assigned which is used to signal the end of the callback execution.
If name is specified, the second argument sent to cb
goes to chain.var
.
example/par.js
var chainr = require('../');
var chain = chainr();
chain
.par(function(cb) {
setTimeout(function() {
console.log('1.1');
cb();
}, 1000);
})
.par('foo', function(cb) {
setTimeout(function() {
console.log('1.2');
cb(null, 'bar');
}, 400);
})
.par(function(cb) {
setTimeout(function() {
console.log('1.3');
cb();
}, 100);
})
.seq(function (cb) {
console.log(chain.vars);
});
Output:
1.3
1.2
1.1
{ foo: 'bar' }
.one(cb)
.one(name, cb)
Functions registered via .one
are executed in parallel.
one
acts equally as par
with the distinction that it does not wait for all callbacks to execute, one call is sufficient.
Each cb
gets a callback assigned which is used to signal the end of the callback execution.
If name is specified, the second argument sent to cb
goes to chain.var
. (Notice that not every value might be in there!)
example/one.js
var chainr = require('../');
var order = [];
var chain = chainr();
chain
.one(function(cb) {
setTimeout(function() {
console.log('1.1');
order.push('1.1');
cb();
}, 1000);
})
.one(function(cb) {
setTimeout(function() {
console.log('1.2');
order.push('1.2');
cb();
}, 400);
})
.one(function(cb) {
setTimeout(function() {
console.log('1.3');
order.push('1.3');
cb();
}, 100);
})
.seq(function (cb) {
console.log(order);
});
Output:
1.3
1.2
1.1
['1.1']
.catch(cb)
When in a sequential or parallel context a callback gets an error object assigned, the execution steps over all pending steps and skips to the next catch
block.
The catch block than receives the error and an callback that can be used to continue with the execution or to rethrow the error.
example/catch.js
var chainr = require('../');
chainr()
.seq(function (cb) {
cb(new Error('foo'));
})
.seq(function (cb) {
console.log('2');
cb();
})
.catch(function (error, cb) {
console.log(error);
cb(error);
})
.catch(function(error, cb) {
console.log(error);
cb();
})
.seq(function() {
console.log('final');
});
Output:
[Error: foo]
[Error: foo]
final
Source Code
github.com/zaphod1984/chainr...Metadata
- MIT
- Whatever
- Manuel Ernst
- released 1/20/2014