Check for truth at a specified interval

README.md

NAME

meanwhile(3)

SYNOPSIS

Some setInterval sugar. A program keeps running, meanwhile a check is performed at a specified interval and if the resut is true, a callback gets called.

EXAMPLE

var meanwhile = require('meanwhile')
var x = false

meanwhile(
  function() { return x },
  function() { console.log('x is now true') }
)

x = true

meanwhile.js

module.exports = function meanwhile(condition, callback, interval, maxTries) {

  if (!meanwhile.collection) {
    meanwhile.collection = []
  }

  function clear(index) {
    clearInterval(meanwhile.collection[index])
    delete meanwhile.collection[index]
  }

  var result = condition()

  if (result) {
    callback(result)
  }
  else {
    meanwhile.collection.push(
      setInterval((function(index) {
        return function() {
          result = condition()
          if (result) {
            clear(index)
            callback(result)
          }
          else if (--maxTries === 0) {
            clear(index)
          }
        }
      })(meanwhile.collection.length), interval || 16)
    )
  }
}

package.json

{
  "name": "meanwhile",
  "version": "0.0.2",
  "description": "check for truth at a specified interval, meanwhile keep working",
  "main": "meanwhile.js",
  "scripts": {
    "test": "node test.js"
  },
  "repository": {
    "type": "git",
    "url": "https://gist.github.com/5105621.git"
  },
  "keywords": [
    "flow"
  ],
  "author": "hij1nx",
  "license": "MIT"
}

test.js

var assert = require('assert');
var meanwhile = require('./meanwhile');

var x = false, y = false

meanwhile(
  function() { return x },
  function() { y = true; assert.ok('The callback was called') }
)

setTimeout(function() {
  x = true
}, 100)

setTimeout(function() {
  if (y === false) {
    assert.fail('The callback was not called')
  }
}, 200)

I did this module to see how it feels to publish to npm from a gist. it works great and feels lite-weight.