Tuan Kuranes Kuranes

What's wrong with Netmag's "Optimize your JavaScript" post

Update: The original post on Netmag has been updated since this was written.

I tweeted earlier that this should be retracted. Generally, these performance-related articles are essentially little more than linkbait -- there are perhaps an infinite number of things you should do to improve a page's performance before worrying about the purported perf hit of multiplication vs. division -- but this post went further than most in this genre: it offered patently inaccurate and misleading advice.

Here are a few examples, assembled by some people who actually know what they're talking about (largely Rick Waldron and Ben Alman, with some help from myself and several others from the place that shall be unnamed).

Things that are just plain wrong

Git hooks for better pivotal integration:

pre-commit:
- prevents commiting on a branch that is not suffixed by an issue number. Some special branches (develop, master) and hotfixes are not constrained
- lints modified python files and exits upon non correctly formatted modules
- other formats (js, scss) have pending code that is not currently called as the workflow for front code is not clear
prepare-commit-msg: prepend issue number to commit message if it's missing and if it is set in the branch name (see pre-commit hook)
post-checkout: [optional] automatically update submodules when checkouting a branch (requires to define the AUTO_SUBMODULE_UPDATE environment variable)

For easy setup:

	#define _CRT_SECURE_NO_DEPRECATE

	#include <stdio.h>
	#include <string.h>
	#include <Windows.h>

	// This allocates a "magic ring buffer" that is mapped twice, with the two
	// copies being contiguous in (virtual) memory. The advantage of this is
	// that this allows any function that expects data to be contiguous in
	// memory to read from (or write to) such a buffer. It also means that

	// Type-safe varargs with C++11 variadic templates.
	//
	// Andreas Fredriksson <deplinenoise at gmail dott com>
	//
	// This code is in the public domain.


	#include <stdio.h>
	#include <stdarg.h>

	#define _PCH_LIBC
	#define _PCH_WINDOWS_H
	#define _PCH_EXTLIB

	#ifdef _PCH_LIBC

	#include <cassert>
	#include <cctype>
	#include <cerrno>
	#include <cfloat>

	// total number of samples at each fragment
	#define NUM_SAMPLES {{ numSamples }}

	#define NUM_SPIRAL_TURNS {{ numSpiralTurns }}

	#define USE_ACTUAL_NORMALS {{ useActualNormals }}

	#define VARIATION {{ variation }}

	uniform sampler2D sGBuffer;

	// number of directions to sample in UV space
	#define NUM_SAMPLE_DIRECTIONS {{ numSampleDirections }}

	// number of sample steps when raymarching along a direction
	#define NUM_SAMPLE_STEPS {{ numSampleSteps }}

	#define APPLY_ATTENUATION {{ attenuation }}

	#define USE_ACTUAL_NORMALS {{ useActualNormals }}

	// Load an image in your browser and paste this in your console

	var i=new Image();i.src=document.location.href;i.onload=function(){var c=document.createElement('canvas');c.width=this.width;c.height=this.height;c.getContext('2d').drawImage(this,0,0);window.location=c.toDataURL('image/png');};

	#define SAMPLE_COUNT {{ sampleCount }}
	#define USE_ACTUAL_NORMALS {{ useActualNormals }}

	uniform sampler2D sGBuffer;
	uniform sampler2D sNoise;

	uniform float uSampleRadius;
	uniform float uIntensity;
	uniform vec2 uNoiseScale;
	uniform vec3 uKernel[SAMPLE_COUNT];

	//
	// AppDelegate.m
	// Upload to Sketchfab sample code
	//
	// Created by Pierre-Antoine Passet on 11/26/13.
	// Copyright (c) 2013 Sketchfab. All rights reserved.
	//

	#import "AppDelegate.h"
	#import "AFHTTPRequestOperation.h"