This minimalistic example provides you with a function to shuffle strings. That is, returned string contains all characters from source string, but mixed in random order.
Code follows,
/// string_shuffle(string) // Returns a string with contents shuffled. var r, i; r = ''; i = 1; // for each character in source, repeat (string_length(argument0)) { // insert character at random // position into destination string r = string_insert( string_char_at(argument0, i), r, irandom(i)); i += 1; } return r;