Utilz - Various Small Utility Functions for Node.js

Usage

npm install utilz

var utilz = require('utilz');

Examples

watchFile(fileName)

Watch the specificed .js file and quit the server to restart if it has changed. Best used with Supervisord, or Forever (when it matures).

• fileName: the file to watch, may be relative to process.cwd().

utilz.watchFile(__filename); // watch this .js
utilz.watchFile(__dirname + '/other.js'); // watch some other .js

In production (NODE_ENV === 'production'), this will not restart imediatelly, but rather wait 2 seconds, to allow for all files to be replaced first, in the case of a full update.

timeSpan(timespanInMs)

Display time duration in human readable format, from number of days to milliseconds.

• timespanInMs: the time interval in milliseconds.

var t1 = Date.now();
var t2 = new Date('Mon, 21 Dec 2012 21:20:12 GMT').getTime();
 
console.log(utilz.timeSpan(t2 - t1));

This will display an interval in the form of:

368d 11h 41m 17s 57ms

formatNumber(number, fractionDigits)

Format a number to the number of decimal places specified, and add grouping commas.

• number: the number to format.
• fractionDigits: the number of decimal places.

var n = 123456.123456;
 
console.log(utilz.formatNumber(n, 3));
console.log(utilz.formatNumber(n, 0));

This will display:

123,456.123
123,456

sign(obj, secret, timed)

Sign an object using sha256, optionally add timestamp. The sig and ts are reserved property names in the object.

• obj: the object to sign
• secret: the secret key
• timed: boolean, whether to add timestamp for later checking
• return: the signature, which needs to be assigned to obj.sig

See below for complete example.

verify(obj, secret, timeWindowMs)

Verify a sha256 signed object, optionally check if timestamp falls into the specified window.

• obj: the object to verify
• secret: the secret key
• timeWindowMs: optional, the time window tolerance for the timestamp, in milliseconds
• return: error message or null on success

var utilz = require('utilz');
var laeh = require('laeh');
var _e = laeh._e;
var _x = laeh._x;
 
var obj = { f: 'my func', a: 'data 1', b: 'data 2' };
 
console.log(obj);
 
obj.sig = utilz.sign(obj, 'my secret', true);
 
console.log(obj);
 
_e(utilz.verify(obj, 'my secret', 5000));
 
console.log('success');

This will print:

{ f: 'my func', a: 'data 1', b: 'data 2' }
{ f: 'my func', a: 'data 1', b: 'data 2', ts: 1324557616927, 
	sig: '1adb63e40223fe95a543983de5c4b4d164a84c05af3effebd1157c50e5b1a533' }
success

mongodbInit(mongodb, dbName, srvHost, srvPort, config, cb)

Initialize mongodb (node-mongodb-native) indexes for a specific collection.

• mongodb: the mongodb module
• dbName: name of the database you want to use
• srvHost: the computer running mongod
• srvPort: the port mongod listens at
• config: config object with collection names and their indexes, see below
• cb: finish callback in form of function(err, db), where the db is the initialized mongo database

var mongo = require('mongo');
 
var cfg = {
    opts: { safe: true }, // options for the mongodb driver
    col1: [[ 'email' ]],
    col2: [[ 'created' ], [ 'name' ], [ 'age' ]]
};
 
utilz.mongodbInit(mongodb, 'amazorro', 'localhost', 27017, cfg, function(err, db) {
 
    if(err)
        throw err;
 
    // the collections are now usable at db.col1 and db.col2, e.g.:
    db.col1.find({ email: 'abc@def.com' }).toArray(function(err, arr) {
        console.log(arr);
        db.close();
    });
 
});

mongodbFAMCheck(err, msg)

Special treatment for mongodb's findAndModify(), when the object is not found.

When you use findAndModify with a query which finds no object, mongo reports this as object not found, which you may find misleading as with all other functions, the result is simply set to null. Additionaly, the message "object not found" is too generic to provide any value. This little function will simply isolate this special case and allows you attach your special message to it. Make sure to instruct _x to not intercept the err parameter, as in this case the mongodbFAMCheck fully takes over.

col.findAndModify(query, sort, update, { new: true }, _x(cb, false, function(err, result) {
    utilz.mongodbFAMCheck(err, 'Concurrent record allocation; sending the client over');
    ...
}));

randomString(opts)

Generate a random string based on the passed options. Example options (the probabilities are checked from smallest to largest via less-than-or-equal):

{
    length: 10,
    ratios: [
        { type: 'numeric', probability: .2 },
        { type: 'upper', probability: .6 },
        { type: 'lower', probability: 1 }
    ]
}

More...

More functions will be added in the future.