Page Comparison

my_str = "This is a string";
a = my_str.match(re/is/re#is#) // a = true
b = my_str.match(re/mouse/re#mouse#) // b = false

my_str = "This is a string";
my_url = "http://www.amazon.com/gp/products/123456789/";
a = my_str.replace(re/is/re#is#,"ese");                            // a = "These is a string"
b = my_str.replace(re/is/gre#is#g,"ese");                           // b = "These ese a string"
c = my_str.replace(re/this/re#this#,"That");                         // c = "This is a string" (no change)
d = my_str.replace(re/this/ire#this#i,"That");                        // d = "That is a string"
e = my_url.replace(re#^http://(\[A-Za-z0-9.-\]+)/.*#,"$1");  // e = "www.amazon.com"

a = "A;B;C"
c = a.split(re/re#;/#) // c = ["A","B","C"]