Merge branch 'master' of github.com:coffeescript-cookbook/coffeescript-cookbook.github.com

Author: thirdtruck

chapters/arrays/using-arrays-to-swap-variables.textile

@@ -0,0 +1,52 @@
+---
+layout: recipe
+title: Using Arrays to Swap Variables
+chapter: Arrays
+---
+
+h1. Using Arrays to Swap Variables
+
+h2. Problem
+
+You want to use an array to swap variables.
+
+h2. Solution
+
+Use CoffeeScript's "destructuring assignment":http://jashkenas.github.com/coffee-script/#destructuring syntax:
+
+{% highlight coffeescript %}
+a = 1
+b = 3
+
+[a, b] = [b, a]
+
+a
+# => 3
+
+b
+# => 1
+{% endhighlight %}
+
+
+h2. Discussion
+
+Destructuring assignment allows swapping two values without the use of a temporary variable.
+
+This can be useful when traversing arrays and ensuring iteration only happens over the shortest one:
+
+{% highlight coffeescript %}
+
+ray1 = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
+ray2 = [ 5, 9, 14, 20 ]
+
+intersection = (a, b) ->
+  [a, b] = [b, a] if a.length > b.length
+  value for value in a when value in b
+
+intersection ray1, ray2
+# => [ 5, 9 ]
+
+intersection ray2, ray1
+# => [ 5, 9 ]
+
+{% endhighlight %}

chapters/dates_and_times/days-between-two-dates.textile

@@ -0,0 +1,41 @@
+---
+layout: recipe
+title: Get Days Between two Dates
+chapter: Dates and Times
+---
+
+h2. Problem
+
+You need to find how much seconds minutes, hours, days, months or years has passed between two dates.
+
+h2. Solution
+
+Use JavaScript's Date function  getTime(). Which provides how much time in miliseconds has passed since 01/01/1970:
+
+{% highlight coffeescript %}
+DAY = 1000 * 60 * 60  * 24
+
+d1 = new Date('02/01/2011')
+d2 = new Date('02/06/2011')
+
+days_passed = Math.round((d2.getTime() - d1.getTime()) / DAY)
+{% endhighlight %}
+
+h2. Discussion
+
+Using miliseconds makes the life easier to avoid overflow mistakes with Dates. So we first calculate how much miliseconds has a day.
+Then, given two distincit dates, just get the diference in miliseconds betwen two dates and then divide by how much miliseconds has a 
+day. It will get you the days between two distinct dates.
+
+If you'd like to calculate the hours between two dates objects you can do that just by dividing the diference in miliseconds by the
+convertion of miliseconds to hours. The same goes to minutes and seconds.
+
+{% highlight coffeescript %}
+HOUR = 1000 * 60 * 60
+
+d1 = new Date('02/01/2011 02:20')
+d2 = new Date('02/06/2011 05:20')
+
+hour_passed = Math.round((d2.getTime() - d1.getTime()) / HOUR)
+{% endhighlight %}
+

chapters/regular_expressions/heregexes.textile

@@ -25,3 +25,12 @@ pattern = ///
 h2. Discussion
 
 Breaking up your complex regular expressions and commenting key sections makes them a lot more decipherable and maintainable. For example, changing this regex to allow an optional space between the prefix and line number would now be fairly obvious.
+
+h3. Whitespace characters in heregexes
+
+Whitespace is ignored in heregexes -- so what do you do if you need to match a
+literal ASCII space?
+
+One solution is to use the @\s@ character class, which will match spaces, tabs
+and line breaks. If you only want to match a space, though, you'll need to use
+@\x20@ to denote a literal ASCII space.

chapters/strings/splitting-a-string.textile

@@ -0,0 +1,37 @@
+---
+layout: recipe
+title: Splitting a String
+chapter: Strings
+---
+
+h2. Problem
+
+You want to split a string.
+
+h2. Solution
+
+Use JavaScript's String split() method:
+
+{% highlight coffeescript %}
+"foo bar baz".split " "
+# => [ 'foo', 'bar', 'baz' ]
+{% endhighlight %}
+
+h2. Discussion
+
+String's split() is a standard JavaScript method. It can be used to split a string on any delimiter, including regular expressions. It also accepts a second parameter that specifies the number of splits to return.
+
+{% highlight coffeescript %}
+"foo-bar-baz".split "-"
+# => [ 'foo', 'bar', 'baz' ]
+{% endhighlight %}
+
+{% highlight coffeescript %}
+"foo   bar  \t baz".split /\s+/
+# => [ 'foo', 'bar', 'baz' ]
+{% endhighlight %}
+
+{% highlight coffeescript %}
+"the sun goes down and I sit on the old broken-down river pier".split " ", 2
+# => [ 'the', 'sun' ]
+{% endhighlight %}

wanted-recipes.textile

@@ -17,7 +17,6 @@ h2. Objects
 h2. Strings
 
 * HTML methods # JS .sup(), .sub(), .blink(), .link(url), etc. May not exist in your JS impl!
-* Splitting a string # JS "foo bar baz".split ' ' # => [ 'foo', 'bar', 'baz' ]
 * substr # str.substr(x,y)  === str[x..x+y-1] === str[x...x+y]
 * substring # str.substring(x,y) === str.slice(x,y)  === str[x..y-1] === str[x...y]
 * Uppercasing a string # JS toUpperCase()
@@ -27,7 +26,6 @@ h2. Strings
 
 h2. Arrays
 
-* Using Arrays to Swap Variables # [x,y] = [y,x]
 * Reducing arrays to values (ruby inject) with reduce # [1..10].reduce (a,b) -> a+b # 55
 * Reducing arrays in reverse order # JS reduceRight 
 {% highlight coffeescript %}