Merge pull request coffeescript-cookbook#6 from AaronW/master

Degrees and Radians

Author: peterhellberg

chapters/math/radians-degrees.textile

@@ -0,0 +1,33 @@
+---
+layout: recipe
+title: Converting Radians and Degrees
+chapter: Math
+---
+
+h2. Problem
+
+You need to convert between radians and degrees.
+
+h2. Solution
+
+Use Javascript's Math.PI and a simple formula to convert between the two.
+
+{% highlight coffeescript %}
+# To convert from radians to degrees
+radiansToDegrees = (radians) ->
+    degrees = radians * 180 / Math.PI
+
+radiansToDegrees(1)
+# => 57.29577951308232
+
+# To convert from degrees to radians
+degreesToRadians = (degrees) ->
+    radians = degrees * Math.PI / 180
+
+degreesToRadians(1)
+# => 0.017453292519943295
+{% endhighlight %}
+
+h2. Discussion
+
+Questions?

chapters/strings/finding-substrings.textile

@@ -0,0 +1,32 @@
+---
+layout: recipe
+title: Finding Substrings
+chapter: Strings
+---
+
+h2. Problem
+
+You need to find the first or last occurrence of a search string within a message.
+
+h2. Solution
+
+Use Javascript's indexOf() and lastIndexOf() to find the first and last occurrences of a string, respectively.
+Syntax: string.indexOf(searchstring, start)
+
+{% highlight coffeescript %}
+message = "This is a test string. This has a repeat or two. This might even have a third."
+message.indexOf("This",0)
+# => 0
+
+# Modifying the start parameter
+message.indexOf("This",5)
+# => 23
+
+message.lastIndexOf("This")
+# => 49
+
+{% endhighlight %}
+
+h2. Discussion
+
+Still need recipe to count occurrences of a given string within a message.

chapters/syntax/for_loops.textile

@@ -0,0 +1,30 @@
+---
+layout: recipe
+title: For Loops
+chapter: Syntax
+---
+
+h2. Problem
+
+You need to iterate over an array, object or range with a for loop.
+
+h2. Solution
+
+{% highlight coffeescript %}
+# for(i = 1; i<= 10; i++)
+x for x in [1..10]
+# => [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]
+
+# To count by 2
+# for(i=1; i<= 10; i=i+2)
+x for x in [1..10] by 2
+# => [ 1, 3, 5, 7, 9 ]
+
+# Perform a simple operation like squaring each item.
+x * x for x in [1..10]
+# = > [1,4,9,16,25,36,49,64,81,100]
+{% endhighlight %}
+
+h2. Discussion
+
+Comprehensions replace for loops in CoffeeScript, but they simply compile into the traditional javascript equivalent for-loop.

wanted-recipes.textile

@@ -10,8 +10,6 @@ In the notes below, "JS" means the recipe is just a simple passthrough to an exi
 
 h2. Syntax
 
-* loops: for x in [1..10]
-* loops: for x in [1..10] then do_one_thing
 * list comp gotcha: y = x for x in [1..3]; y # => 3; but y = (x for x in [1..3]); y # => [ 1, 2, 3 ]
 * Ensuring variables are closed over # with "do"
 
@@ -21,7 +19,6 @@ h2. Objects
 
 h2. Strings
 
-* Find a substring in a string  # not by regex! JS indexOf(), lastIndexOf()
 * 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]
@@ -59,7 +56,6 @@ h2. Dates and Times
 
 h2. Math
 
-* Converting between degrees and radians
 * square root # JS Math.sqrt
 * Constants # JS Math.PI, Math.E
 * floor, ceil, round # JS Math.floor, Math.ceil, Math.round