Emulate slow network connection on Mac OS X with Network Link Conditioner

1. Open https://developer.apple.com/download/more/ (Downloads For Apple Developers)
2. Find and download Additional Tools for Xcode 8.2 (or other Xcode version you use). Note that there is no need to download/install Xcode itself.
3. Open Additional Tools - Hardware - double-click on Network Link Conditioner
4. Agree to install it to Preferences

Available Network Profiles:

• 100% Loss - drops all incoming and outgoing packets 
• High Latency DNS - adds 3000 ms DNS delay 
• Very Bad Network - 1 Mbps 500ms delay downlink, 1 Mbps 500 ms delay uplink, and 10% of incoming and outgoing packets are dropped
• Edge - 240 Kpbs 400 ms delay downlink, 200 Kbps 440 ms delay uplink
• 3G - 780 Kpbs 100 ms delay downlink, 330 Kbps 100 ms delay uplink
• DSL - 2 Mbps 5ms delay downlink, 256 Kbps 5 ms delay uplink
• LTE - 50 Mbps 50ms delay downlink, 10 Mbps 65 ms delay uplink
• Wi-Fi - 40 Mbps 1ms delay downlink, 33 Mbps 1 ms delay uplink
• Wi-Fi 802.11ac - 250 Mbps 1ms delay downlink, 100 Mbps 1 ms delay uplink

Also there is an option to create custom profiles.

EcmaScript support in Node

Interestingly enough, even 9.0.0 nightlies don't support ES2015 fully: it's missing tail call optimization, Array.prototype.values, and RegExp.prototype.flags.
http://node.green/ - ES2015 ES2016 ES2017 compatibility tables for Node.

List all the in progress features available on your Node release:
node --v8-options | grep "in progress"

List all dependencies and respective versions that ship with a specific Node binary:
node -p process.versions.v8
https://nodejs.org/en/docs/es6/

Get Pseudo-Element Properties with JavaScript

Assume your CSS looks like:

.element:before {

    content: 'NEW';

    color: rgb(255, 0, 0);

}

To retrieve the color property of the .element:before, you could use the following JavaScript:

var color = window

    .getComputedStyle(document.querySelector('.element'), ':before')

    .getPropertyValue('color')

Passing the pseudo-element as the second argument to window.getComputedStyle allows access to said pseudo-element styles

Original post

MDN

Mouse and keyboard support in Midnight Commander for Mac OS X

Somehow I broke mouse support in Midnight Commander while setting up a fresh Mac OS X. It took me the whole week to find the root cause and enable mouse in MC again. Here is the checklist:

• Check that Mouse Reporting is enabled
  Terminal - Menu - View or Cmd+R hotkey
• Find the value of TERM env variable
  echo $TERM in terminal or open Terminal Settings (Cmd+,), go to Profiles - look for Terminfo; it was set to xterm-256color in my case
• Quit all Midnight Commander instances, if any
• Edit ~/.config/mc/ini file, find corresponding terminal section, e.g. [xterm-256color] for my terminal, and remove all its entries
• Start Midnight Commander

Keyboard support: to make Shift+Up and Shift+Down keys work in Midnight Commander, do the following:

• Open Terminal Settings - Keyboard tab
• Add Shift+Up - send text "\033[1;2A" (copy from Shift+Left and edit text)
• Add Shift+Down - send text "\033[1;2B"