A practical walkthrough of using map/reduce with MongoDB to aggregate statistics for generating a report.
Ben Cherry, web developer at Twitter, takes us step by step through the Module Pattern. He introduces the standard features of Anonymous Closures and avoiding global scope, and covers advanced concepts such as augmentation, cloning, inheritance, private state and sub-modules.
A simplified explanation of closures by Morris Johns: A closure is the local variables for a function - kept alive after the function has returned.
A stackoverflow community article explaining closures in plain simple English does a great job. Succinctly: a closure is created when inner function that gets returned. The inner function can still see the variables and methods defined in the outer function.
Angus Croll covers the new 'use strict' operator introduces in EcmaScript 5th edition and how to get started using it. He offers a set of unit test to see how well supported strict mode is in your browser.
Douglas Crockford explains the new strict mode introduced in the 5th edition of ECMAScript. It is an opt-in mode that repairs or removes some of the language's most problematic features such as: function scoping, implied global variables and global leakage, read-only variable failures, octal defaults and function arguments.
PPK describes the this keyword as a reference to the owner of the function we are executing, or the object that a function is a method of. He then compares how attaching a function to an event in two different ways affects what the this keyword references.
Fellow co-worker Lawrence Carvalho discusses the Undo functionality, and as web based applications start to replace desktop ones, this crucial bit of functionality will become expected by application users. Lawrence talks about the Memento design pattern and guides us through designing objects that can undo their changes. He builds an undoable text widget.
Jim Ley covers the intricacies of type conversion, implicit and explicit. He covers type conversion into boolean, string, number, undefined, null; and parsing into floats and integers. This is backed up by conversion tables for quick reference. There's also a useful section on regular expressions for form field validation.
map() function, which is similar to Prototype's
this keyword is being used in the code. Snook offers workarounds to this by passing objects so that the context is correct, or using the
call() function to ensure the context is correct.
Dan Webb describes curried functions as a way of creating reusable callback functions for event handlers or Ajax requests, or anything that takes a function as an argument. By using closures, curried functions have a simple way of persisting data between calls. He also offers an elegant way of running a lots of methods on objects, with a simple map function written as a curried function.
Tim describes another two different approaches to using the Module Pattern (a way of creating Singletons). The first example takes advantage of the natural indentation to clearly see which methods are private and which are public. The second is a curried function, a function that returns another function.
David Dorward compares dot notation and square bracket notation, where square bracket notation can be used where dot notation can't. Recommends using dot notation, because its easier to read, and square bracket notation when it can't be done with dot notation.
The Yahoo! Web Developer Network provides a one page overview of JSON, giving a quick tutorial on JSON, how to get Yahoo! Web services to emit JSON, offering an output of a JSON object literal as well as using a callback function method. Yahoo! also describes how their web services typically translate their XML structures into JSON.
Christian Heilmann offers another incremental improvement to the Module Pattern, and calls it the Revealing Module Pattern. This defines an anonymous object that contains a list of methods and properties that are publicly available. Christian notes that this method also allows you to set up a public property that's privately generated by a method. Christian's improvement makes it quickly clear which properties and methods are public.
Christian Heilmann compares the Object Literal to Douglas Crockford's Module pattern and finds that the Module pattern fixes a major problem of the object literal - the difficult choice of using this or fully qualified references to functions in the same block. Christian also covers the improvements in the Module Pattern, like the decluttering of the return block, which makes the resulting a little easier to work with.
An evolt article that covers using Regular Expressions, including the difference between static and dynamic regular expressions (compiled at compile time or runtime respectively). Good selection of tables such as regex modifiers, patterns and escaping, look ahead, backreferences. Includes a short section on usage. A neat short cheatsheet for starting to use regular expressions.
As web pages become more and more like applications, code performance becomes more and more important. This article looks at a number of performance issues to avoid, in EcmaScript, DOM and AJAX requests. Covers eval, the with keyword, try/catch in performance-critical code, global variables, implicit object conversion, string concatenation, primitive operations over function calls, repainting and reflowing documents, modifying elements, using XPath.
An online copy of O'Reilly's 2002 book Creating Applications with Mozilla. It focused on pre-1.0 versions of Mozilla, so details about the application structure has changed, but the XUL elements are relatively stable.
Instead of creating a new XmlHttpRequest object for every request, this post provides code to pool these objects together and reuse them. This saves a great deal of processing times, particularly in IE.
Guides, notes, overviews, documentation for the Prototype library. Pathfinder compiles a list of useful resources for this library.
Ryan Campbell shows how to get the Prototype library up and running, and introduces and documents Protoype's $() function. Form helper functions, getElementsByClassName functions, Element helper functions, Ajax support, timer functions are all covered.
A collection of performance related techniques, including temporary references (for deeply namespaced properties), optimising loops by referencing the collection length once, reasons to avoid the with syntax, using null over the delete function, comparison for equality and identity and short-circuit logical expressions
Comparing three methods of URI encoding. Escape() is probably best avoided, with encodeURI() and encodeURIComponent() being used depending on what form your data is in.
As well as supporting CSS based selectors, jQuery also supports XPath expressions. This page lists a plethora of code snippets demonstrating jQuery's XPath matching capabilities.
A list of the CSS Selectors supported by jQuery. It includes the regular gamut of CSS selectors as well as attribute selectors, pseudo-selectors and child selectors.