nseq v0.1.0

nseq

Introduction

nseq is a module to simplify the usage of callbacks at Node.Js. This module will not replace the call backs usage, but will simplify it. Also will reduce the number of infinite indentations, when need to make many functions that depends from call back.

Install

npm install nseq

Example of how it works

var nseq = require('nseq');
// 1 - Create a new instance
s = new nseq();
// 2 - Do a sequence of functions
s.do([
  function(self) {
    // 3 -  Do any callback execution
    any_call_back_execution(function() {
      // 4 - When complete, call self.next
      self.next();
    });
  },
  function(self) {
    // 5 - Continue executing the callbacks as you need.
    any_other_call_back_execution(function(name, date_of_birth) {
      // 6 - Do what you need, before from call the next.
      var age = dob2a(date_of_birth);
      // 7 - Set arguments for the next sequence
      self.next(name, age);
    });
  },
  function(self, name, age) {
    // 8 - Arguments passed in the last sequence will arrive in the current
    // 9 - Continue your code....
    self.next();
  }
]);

Methods

constructor(options)

Constructor can be used to set parameters to be used in the sequences.

Parameter

options : (optional): An object with variables. Each variable will be accessible as self.name_of_variable

Return

Null

Example

var s = new nseq({
     "test_number": 1,
     "test_string"   : "myVal"
  });
s.add([
  function (self) {
    console.log("Number",self.test_number);
    console.log("String",self.test_string);
  },
...

add(function_array_list)

Add sequences with out execute.

Parameter

function_array_list : A list of functions to be executed.

Return

nseq object will be returned, what allow to chain other methods.

Example

var s = new nseq();
s.add([
  function (self) {
    console.log("This is my 1st sequence");
    self.next();
  },function (self) {
    console.log("This is my 2nd sequence");
    self.next();
  },function (self) {
    console.log("This is my 3rd sequence");
    self.next();
  }
]);
s.do();

do(function_array_list)

Execute the list of sequences. If a function_array_list be passed, then first add this to the list of sequences, and then execute.

Parameter

function_array_list (optional) : A list of functions to be executed.

Return

nseq object will be returned, what allow to chain other methods.

Example

var s = new nseq();
s.do([
  function (self) {
    console.log("This is my 1st sequence");
    self.next();
  },function (self) {
    console.log("This is my 2nd sequence");
    self.next();
  },function (self) {
    console.log("This is my 3rd sequence");
    self.next();
  }
]);

clone()

Colne an existing nseq object. Useful to run the same sequence of functions with different parameters.

Parameter

None.

Return

A new nseq object.

Example

var s = new nseq();
s.add([
  function (self) {
    console.log("This is my 1st sequence, with user name:", self.username);
    self.next();
  },function (self) {
    console.log("This is my 2nd sequence, with user name:", self.username);
    self.next();
  }
]);
s.username = "Jhon";
var s2 = s.clone();
s2.username = "Ana";
s.do();
s2.do2();

end = function

Set the end propriety with a function to be executed with all sequences finish.

Example

var s = new nseq();
s.end = function(self,data){
  console.log("My Data", data);
};
s.add([
  function (self) {
    console.log("This is my 1st sequence");
    self.next();
  },function (self) {
    console.log("This is my 2nd sequence");
    self.next();
  },function (self) {
    console.log("This is my 3rd sequence");
    # As there are no more sequences, then it will call `end` function.
    self.next({"number":123});
  }
]);

More Examples

Simple example

s = new nseq();
s.do([
  function(self) {
    var num = 1;
    // Example of a setTimeout call back
    setTimeout {
      function() {
        num = num + 1;
        // When complete the task, call self.next, passing any argument.
        self.next(num);
      }
    }
  },
  function(self, num) {
    // The arguments passed in the previous sequence will arrive in the next.
    // In this example, is the "num"

    // Do any other task
    num = num + 1;

    // Can call more sequences if needed.
    self.next(num);
  }
]);

Full example

var nseq = require('nseq');
// Create a new instance
s = new nseq();

// ...
connection.connect();

// Add the functions sequence, but with out execute.
s.add([
  function(self) {
    // Get user id
    connection.query('SELECT user_id from user_table where name=?', [self.username], function(err, rows, fields) {
      if (err) throw err;
      self.next(rows[0].user_id);
    });
  },
  function(self, user_id) {
    // Get session_id
    connection.query('SELECT session_id from session_table where id=?', [user_id], function(err, rows, fields) {
      if (err) throw err;
      if(rows.length > 0){
        self.next(rows[0].session_id, user_id); 
      }else{
        self.end("session not found");
      }
    });
  },
  function(self, session_id, user_id) {
    // Get user data
    connection.query('SELECT * from data_table where session=? and user=?', [session_id, user_id], function(err, rows, fields) {
      self.end(err, rows[0]);
    });
  }
]);
// Set parameters, it will be accessible as self.username
s.username = "petter";
// Set a function, to when finish.
s.end = function(err,data){
  if (err) throw err;
  console.log("user data:", data);
}
// Start the execution
s.do();