The poor, misunderstood innerText — Perfection Kills
The poor, misunderstood innerText Few things are as misunderstood and misused on the web as innerText property. That quirky, non-standard way of element's text retrieval, [introduced by Internet Explorer](https://msdn.microsoft.com/en-us/library/ie/ms533899%28v=vs.85%29.aspx) and later "copied" by both WebKit/Blink and Opera for web-compatibility reasons. It's usually seen in combination with text
Javascript quiz. ES6 edition. — Perfection Kills
Javascript quiz. ES6 edition. Remember that crazy Javascript quiz from 6 years ago? Craving to solve another set of mind-bending snippets no sensible developer would ever use in their code? Looking for a new installment of the most ridiculous Javascript interview questions? Look no further! The "ECMAScript Two Thousand Fifteen" installment of good old Javascript Quiz is finally here. The rules are
State of function decompilation in Javascript — Perfection Kills
State of function decompilation in Javascript It’s always fun to see something described as “magic” in Javascript world. One such example I came across recently was AngularJS dependency injection mechanism. I’ve never been familiar with the concept, but seeing it in practice looked clever and convenient. Not very magical though. What is it about? In short: defining required “modules” via function
How ECMAScript 5 still does not allow to subclass array — Perfection Kills
Why subclass an array? Naive approach Problems with naive approach Special nature of arrays Function objects and [[Construct]] The importance of array special behavior Existing solutions ECMAScript 5 accessors to the rescue [[Class]] limitations Does [[Class]] matter? Wrappers. Direct property injection. Wrappers. Prototype chain injection. Summary Subclassing an array in Javascript has never been
Profiling CSS for fun and profit — Perfection Kills
I’ve been recently working on optimizing performance of a so-called one-page web app. The application was highly dynamic, interactive, and was heavily stuffed with new CSS3 goodness. I’m not talking just border-radius and gradients. It was a full stack of shadows, gradients, transforms, sprinkled with transitions, smooth half-transparent colors, clever pseudo-element -based CSS tricks, and experim
Refactoring Javascript with kratko.js — Perfection Kills
Understanding the concept of code refactoring is one of the best things you can do to become a better programmer [1]. It all started a couple of weeks ago when I — once again — looked at the growing, stinky mess that my code has become. It’s a few thousand LOC app with various interactive widgets and controls all on one page. Even though a lot of functionality was encapsulated in these separately-
instanceof considered harmful or how to write a robust isArray — Perfection Kills
`instanceof` considered harmful (or how to write a robust `isArray`) Checking types in Javascript is well known as a pretty unreliable process. Good old typeof operator is often useless when it comes to certain types of values: typeof null; // "object" typeof []; // "object" People often expect to see something like “null” in the former check and something like “array” in the latter one. Fortunate
Detecting event support without browser sniffing — Perfection Kills
One of the pain points of feature testing in client-side scripting is that for event support. DOM doesn’t really specify any means to detect exactly which events browser understands and can work with. If you’d like to know if a browser supports, say, “dblclick” event, you’re pretty much out of luck. This is probably the reason why so many scripts on the web employ unreliable browser sniffing in su
Global eval. What are the options? — Perfection Kills
How eval works Eval’ing in global scope Indirect eval call. Theory. Indirect eval call examples. Indirect eval call. In practice. window.execScript window.eval eval context in webkit new Function setTimeout Script insertion The problem with `window.execScript || eval` Feature testing -based approach Global eval in libraries Summary David Flanagan recently wrote about global eval() in Javascript, p
Understanding delete — Perfection Kills
Theory Type of code Execution context Activation object / Variable object Property attributes Built-ins and DontDelete Undeclared assignments Firebug confusion Deleting variables via eval Browsers compliance Gecko DontDelete bug IE bugs Misconceptions `delete` and host objects ES5 strict mode Summary A couple of weeks ago, I had a chance to glance through Stoyan Stefanov’s Object-Oriented Javascri
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Know thy reference — Perfection Kills