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A simple control flow library.
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README.md

node-chain-tiny

A simple control flow library.

The problem which this library solves is the nest and error handling of callback.

For exsample.

asyncFunc1(function(err, result1) {
  if (err) return callback(err);
  // do something
  asyncFunc2(function(err, result2) {
    if (err) return callback(err);
    // do something
    asyncFunc3(function(err, result3) {
      if (err) return callback(err);
      // do something
      callback(null, result);
    });
  });
});

This code becomes like this by using chain-tiny.

chain(function(next) {
  asyncFunc1(next);
})
.chain(function(result1, next) {
  // do something
  asyncFunc2(next);
})
.chain(function(result2, next) {
  // do something
  asyncFunc3(next);
})
.end(function(err, result3) {
  // do something
  callback(err, result);
});

Install

$ npm install chain-tiny

Usage

simple

var chain = require('chain-tiny');

chain(function(next) {
  setTimeout(function() {
    next(null, 'foo');
  }, 100);
})
.chain(function(foo, next) {
  console.log(foo); // => foo
  setTimeout(function() {
    next(null, 'bar', 'baz');
  }, 1);
})
.end(function(err, bar, baz) {
  console.log(bar); // => bar
  console.log(baz); // => baz
});

error handling

var chain = require('chain-tiny');

chain(function(next) {
  next('Error!');
})
.chain(function(next) {
  // no exec here
  next(null, 'foo');
})
.end(function(err, foo) {
  console.log(foo); // => undefined
  console.log(err); // => Error!
});

forEach

var chain = require('chain-tiny');

// static method
chain.forEach(['foo', 'bar'], function(i, val, next) {
  setTimeout(function() {
    next(null, i + ':' + val);
  }, 1);
})
.end(function(err, results) { // or .chain(results, next)
  console.log(results); // => [ '0:foo', '1:bar' ]
});

// instance method
chain(function(next) {
  next(null, ['foo', 'bar']);
})
.forEach(function(i, val, next) {
  setTimeout(function() {
    next(null, i + ':' + val);
  }, 1);
})
.end(function(err, results) {
  console.log(results); // => [ '0:foo', '1:bar' ]
});

parallel

var r = [];
chain.parallel({
  foo: function(next) {
    setTimeout(function() {
      r.push(1);
      next(null, 1);
    }, 100);
  },
  bar: function(next) {
    setTimeout(function() {
      r.push(2);
      next(null, 2);
    }, 1)
  }
})
.end(function(err, results) {
  console.log(results); // => { foo: 1, bar: 2 }
  console.log(r); // => [2, 1]
});

Functions

Chain

chain(callback)

Constructor. Same these.

chain(fn);
chain().chain(fn);

Parameters

  • callback ( optional function )

Chain.prototype.chain

.chain(callback)

This method only push stack. The function pushed to stack is executed when end() is called.

Parameters

  • callback ( function )

Chain.prototype.parallel

.parallel(obj)

Parallel exec functions.

Parameters

  • obj ( Plain Object or Array )

Chain.prototype.end

.end(callback)

Execute all functions, in the pushed order.

Parameters

  • callback ( function )

Chain.prototype.forEach

.forEach(callback)

Iterator function to each item in an array. Array recieved before next function args.

Parameters

  • callback ( function )

Chain.prototype.forEachParallel

.forEachParallel(callback)

Parallel iterator function to each item in an array. Array recieved before next function args.

Parameters

  • callback ( function )

Chain.forEach

chain.forEach(array, callback)

Iterator function to each item in an array.

Parameters

  • array ( array )
  • callback ( function )

Chain.parallel

chain.parallel(obj)

Alias of Chain().parallel(obj)

Parameters

  • obj ( Plain Object or Array )

Chain.forEachParallel

chain.forEachParallel(array, callback)

Parallel iterator function to each item in an array.

Parameters

  • array ( array )
  • callback ( function )

Testing

$ make test
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