gander

Gander at my hooks, ye Mighty, and despair!

Gander, in its most basic form, wraps itself around functions to provide execution times. Times are provided in sub-milliseconds when the precision is available (process.hrtime, performance.now) and milliseconds when not.

Generally, though, gander exposes callbacks that are invoked before and after a function is called so that you can perform thorough investigations and/or mad science.

Gander supports CommonJS/node.js and AMD/require.js imports. You can also use it in your web app via a normal script tag and it will add itself to the window object.

Install

npm install gander

Node.js Example

var gander = require('gander');
var fs = require('fs');

gander(fs, {
  name: 'fs',
  async: true,
  ignore: ['write', 'writeFile']
});

fs.readFile(__filename, function(err, data) {
  /* log messages:
   *  fs.open: 0.543ms
   *  fs.fstat: 0.301ms
   *  fs.read: 0.154ms
   *  fs.close: 0.086ms
   *  fs.readFile: 13.760ms
   */

  fs.writeFile(__filename + '.bak', data, function(err) {
    // Even though 'write' and 'writeFile' are ignored, underlying
    // method calls are logged since they're not ignored

    /* log messages
     *  fs.open: 0.364ms
     *  fs.close: 0.555ms
     */
  });
});

Require.js Example

define(['gander', 'backbone'], function(gander, Backbone) {
  var MyView = Backbone.View.extend({
    events: {
      'click': 'logBoop'
    },

    constructor: function() {
      Backbone.View.apply(this, arguments);
      gander(this, {name: 'MyView', unique: true});
    },

    render: function() {
      this.$el.html('<div>This is a view</div>');
      return this;
    },

    logBoop: function() {
      console.log('boop');
    }
  });

  return MyView;
});

define(['views/myview'], function(MyView) {
  var view = new MyView();

  $('body').append(view.render().el);

  // MyView1.render: 0.109ms

  /*** click the view ***/

  // MyView1.logBoop: 0.287ms
});

Usage

gander(object, [options])

Gander takes an object and wraps all keys and prototype methods so that before and after callbacks are available. By default, the before callback stores a start time. By default, the after callback retrieves the start time and logs the diff in time. These defaults make gander a nice way of doing timing tests.

Options

• name String - The name of the object. This is for your convenience so you can keep track of what's going on.
• unique Boolean - If set to true, gander will add an integer to the end of the name in the cases where the name is reused by multiple instantiated objects.
• async Boolean - If set to true, gander will wrap callbacks where a callback is a function in the last argument position.
• promise Boolean - If set to true, gander will also wrap promises returned from methods on an object.
• ignore Array.<String> - Gander will ignore any function/method with a name in the ignore array.
• before Function(name, method, arg1, arg2, ..., argn) - Gander will call before immediately prior to calling the underlying function. After the name and method parameters is the complete set of parameters passed to the underlying function.
• after:sync Function(name, method, arg1, arg2, ..., argn, returnValue) - Gander will call after immediately after calling the underlying function. The function parameters are the same as before but now include the return value from the underlying function as the last argument.
• after:async Function(name, method, arg1, arg2, ..., argn, callbackArg1, ..., callbackArgn) - Gander will call after immediately prior to calling the underlying callback function. The function parameters to after are the same as before but now include the arguments to be passed to the underlying callback.
• logger Function(name, method, timeInMs) - If you wish to hook into a custom logger, pass in a function that will be called with the name of the object, the method being called, and the timeInMs it took to execute the function.

Before/After Example

var gander = require('gander');

var TestObject = function() {
  this.num = 1;
};

TestObject.prototype.increment = function(val) {
  this.num += val;
  return this.num;
};

var obj = new TestObject();

/**
 *  A horribly contrived example where in `before` we decrement `this.num` by the amount
 *  to be passed in by `val`. `increment` will then return `this.num` to its
 *  original value. The `after` function will then set things right by incrementing
 *  `this.num` by `val`.
 */
gander(obj, {
  name: 'testObject',
  before: function(name, method, val) {
    this.num -= val;
    console.log('before: this.num:', this.num);
  },
  after: function(name, method, val, returnValue) {
    this.num += val;
    console.log('after: this.num:', this.num);
  }
});

obj.increment(2);
console.log('obj.num:', obj.num);

// before: this.num: -1
// after: this.num: 3
// obj.num: 3

Logger Example

var winston = require('winston');
var fs = require('fs');
var gander = require('gander');

gander(fs, {
  async: true,
  logger: function(name, method, timeInMs) {
    winston.info(name + '.' + method, timeInMs);
  }
});

fs.readFile(__filename, function(err, data) {
  /* log messages:
   * info: fs.open 0.491
   * info: fs.fstat 0.782
   * info: fs.read 0.147
   * info: fs.close 0.132
   * info: fs.readFile 16.468
   */
});

The MIT License

Copyright (c) 2014 Michael Maelzer

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.