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timr

cron like job scheduling library

timr Build Status

NPM

NPM

timr offers a scheduling interface for a cron like job execution.

installation

npm install timr

example

var moment = require('moment');
 
var timr = require('timr');
 
var scheduler = timr();
 
////every 15 seconds 
scheduler().every(15).seconds().run(function() {
    console.log( 'every 15 seconds' );
});
 
//start 30 seconds from now, execute every 10 seconds, end in 5 minutes from now 
var from = moment().add('seconds', 30);
var to = moment().add('minutes', 5);
 
scheduler()
    .from(from)
    .to(to)
    .every(10).seconds()
    .run(function() {
        console.log( 'now+30s every 10s until now+5m' );
    });

scheduler

a scheduler holds a collection of tasks. every task is created via the task construction function.

creates a task construction function

var timr = require('timr');
 
var taskConstructor = timr();

the scheduler object is exposed at the task constructor:

var timr = require('timr');
 
var taskConstructor = timr();
 
console.log( taskConstructor.scheduler );

when a attached task is executed, the parent scheduler also emits a execution event

var timr = require('timr');
 
var taskConstructor = timr();
 
//...create some tasks... 
 
taskConstructor.scheduler.on('execute', function(name, task) {
    //universal handler for all tasks attached to the scheduler 
});

task

modifiers

specify how often and when a task should be performed.

when

via the methods .from(timestamp) and .to(timestamp) the period of time can be specified in which the task should be performed. these methods can be used in every combination or can be omitted completely. (which would case a task to run instantly and indefinitely.

how often

the quantifier .every(n) in combination with a interval modifier like .hour(), .minute() etc defines how often a task gets executed.
the n parameter can be omitted, it defaults to 1. (task.every().minute() means that a task is executed once a minute)

for example the expression task.every(2).minutes() executes the task every 2 minutes.

there are five interval modifiers:
.second()
.minute()
.hour()
.day()
.month()

for every modifier also the plural form is valid. (e.g. .minutes() instead of .minute())

creation

tasks geht automatically attached to the parent scheduler object

var myTask = taskConstructor();

there are multiple ways of invoking a task.

anonymous (one callback)

creates the task, configures it to run every minute and runs the callback assigned in the run handler

taskConstructor().every().minute().run(function() { ... });

anonymous (multiple callbacks)

creates the task, configures it to run every minute and runs each callback.

taskConstructor()
  .every().minute()
  .run(function() { ... })
  .run(function() { ... })
  .run(function() { ... });

named (event handler attached to the task)

creates the task, configures it to run every minute and runs the callback assigned in the run handler.

run has to be called.

var myTask = taskConstructor().every().minute();
 
myTask.on('execute', function() {
  // ... 
});
 
myTask.on('execute', function() {
  // ... 
});
 
myTask.run();

event handler attached to the scheduler

creates two anonymous tasks, configures to run the first every minute and the second to run every second hour.

than the events emitted on the scheduler are used to consume the task events.

run has to be called.

taskConstructor().every().minute().run();
taskConstructor().every(2).hours().run();
 
taskConstructor.scheduler.on('execute', function(name, task) {
  // gets invoked every minute and every second hour 
});

tests

npm test