Add new chapter: replacing sub-strings

chapters/strings/replacing-sub-strings.md

@@ -0,0 +1,29 @@
+---
+layout: recipe
+title: Replacing Sub-Strings Within a String
+chapter: Strings
+---
+## Problem
+
+You want to replace a sub-string with a new sub-string.
+
+## Solution
+
+Split the string using the sub-string you want to remove as a delimiter. Then re-join using the new sub-string as the delimiter.
+
+{% highlight coffeescript %}
+"Orange is the new Black".split("Orange").join("Pink")
+# => "Pink is the new Black"
+
+"I am so sad. I cannot believe how sad I am today!".split("sad").join("happy")
+# => "I am so happy. I cannot believe how happy I am today!"
+
+"I am not a crook.".split("not ").join("")
+# => "I am a crook."
+{% endhighlight %}
+
+## Discussion
+
+You can also use regexes. If you're matching an exact string, this way is simpler and 10x faster.
+
+If you use regexes, remember that you must escape certain characters.