Saad Shahd saadshahd

How to append line numbers in front of each line in a file?

Just use cat. No kidding, cat has the -n option to number the output lines, starting at 1:

cat -n file.txt

This works well both on Linux and Mac. Use the shell redirection to keep the output in a new file (don’t override the original file with the redirection though).

Email address syntax validation? Let the browser do it (without regexp)

Here is a simple and robust way to check for the validity of an email address syntax directly in the browser. No need for crazy regular expressions.

e = document.createElement('input')
e.type = 'email'
// check some email addresses
e.value = 'hi@'

DOM: How to select a range of children?

Given the following HTML code:

<ol>
  <li>1</li>
  <li>2</li>
  <li>3</li>
 4

Stuff I wish I'd known sooner about service workers

I recently had several days of extremely frustrating experiences with service workers. Here are a few things I've since learned which would have made my life much easier but which isn't particularly obvious from most of the blog posts and videos I've seen.

I'll add to this list over time – suggested additions welcome in the comments or via twitter.com/rich_harris.

Use Canary for development instead of Chrome stable

~~Chrome 51 has some pretty wild behaviour related to console.log in service workers. Canary doesn't, and it has a load of really good service worker related stuff in devtools.~~

How to get the xs value from Facebook cookie with Google Chrome:

Open www.messenger.com
Open Developer Tools
Click "Application" tab
Click, "Cookies" in the left panel
Click "www.messenger.com"
Copy the value of "xs"

Word of warning

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

Notational Conventions

This section describes the conventions used here to describe type signatures.

A [T] is an array-like value (only ever used read-only in this API), i.e., one with an integer length and whose indexed properties from 0 to length - 1 are of type T.

A type T? should be read as T | undefined -- that is, an optional value that may be undefined.

Realms

AngularJS Directive Attribute Binding Explanation

When using directives, you often need to pass parameters to the directive. This can be done in several ways. The first 3 can be used whether scope is true or false. This is still a WIP, so validate for yourself.

Raw Attribute Strings

<div my-directive="some string" another-param="another string"></div>

	(function() {
	var CSSCriticalPath = function(w, d, opts) {
	var opt = opts \|\| {};
	var css = {};
	var pushCSS = function(r) {
	if(!!css[r.selectorText] === false) css[r.selectorText] = {};
	var styles = r.style.cssText.split(/;(?![A-Za-z0-9])/);
	for(var i = 0; i < styles.length; i++) {
	if(!!styles[i] === false) continue;
	var pair = styles[i].split(": ");