add recipe for trimming whitespace from a string

Author: phlipper

chapters/strings/trimming-whitespace-from-a-string.md

@@ -0,0 +1,67 @@
+---
+layout: recipe
+title: Trimming whitespace from a String
+chapter: Strings
+---
+## Problem
+
+You want to trim whitespace from a string.
+
+## Solution
+
+Use JavaScript's Regular Expression support to replace whitespace.
+
+To trim leading and trailing whitespace, use the following:
+
+{% highlight coffeescript %}
+"  padded string  ".replace /^\s+|\s+$/g, ""
+# => 'padded string'
+{% endhighlight %}
+
+To trim only leading whitespace, use the following:
+
+{% highlight coffeescript %}
+"  padded string  ".replace /^\s+/g, ""
+# => 'padded string  '
+{% endhighlight %}
+
+To trim only trailing whitespace, use the following:
+
+{% highlight coffeescript %}
+"  padded string  ".replace /\s+$/g, ""
+# => '  padded string'
+{% endhighlight %}
+
+## Discussion
+
+Opera, Firefox and Chrome all have a native string prototype `trim` method, and the other browsers could add one as well. For this particular method, I would use the built-in method where possible:
+
+{% highlight coffeescript %}
+trim = (val) ->
+  if String::trim? then val.trim() else val.replace /^\s+|\s+$/g, ""
+
+trim "  padded string  "
+# => 'padded string'
+{% endhighlight %}
+
+
+### Syntax Sugar
+
+You can add some Ruby-like syntax sugar with the following shortcuts:
+
+{% highlight coffeescript %}
+String::strip = -> if String::trim? then @trim() else @replace /^\s+|\s+$/g, ""
+String::lstrip = -> @replace /^\s+/g, ""
+String::rstrip = -> @replace /\s+$/g, ""
+
+"  padded string  ".strip()
+# => 'padded string'
+"  padded string  ".lstrip()
+# => 'padded string  '
+"  padded string  ".rstrip()
+# => '  padded string'
+{% endhighlight %}
+
+For an interesting discussion and benchmarks of JavaScript `trim` performance, see [this blog post][1] by Steve Levithan.
+
+[1] http://blog.stevenlevithan.com/archives/faster-trim-javascript

wanted-recipes.md

@@ -20,7 +20,6 @@ In the notes below, "JS" means the recipe is just a simple passthrough to an exi
 * 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]
 * Replacing substrings
-* Trimming whitespace from the end of a string
 
 ## Arrays