Code of the Day: Sentence Scrambler

Task:
There was a study going out a few years ago that said people can read words that are scrambled if the first and last character are left in place. So to help me practice Test Driven Development, I decided program it.
Example:
Correct: “Create attractive offers to reach the right customers”
Scrambled: “Cterae aacrtvitte offres to recah the rghit couemtrss”

For more information about the study visit: Cambridge Word Scramble Study: It’s Fake Already!

Code:

/**
* @author: Larry Battle
* @date: January 2, 2012
* @purpose: Scrambler - to scramble the alphabetical letters in word in such a way to make it still readable and understandable.
* @note: This can be accomplished by have perversing the word order but mixing up every letter in the word except for the first.
*/
var scrambler = {
	scrambleStr : function( str ){
		if( typeof str !== 'string' ){
			return -1;
		}
		return str.replace( /[^\s]*/g, function( word ){			
			return word ? scrambler.scrambleWord( word ) : word;
		});
	},
	scrambleWord :  function( str ){
		if( typeof str !== 'string' ){
			return str;
		}
		str = str.replace( /[a-z]*/ig, function( str2 ){
			if( str2 && str2.length > 2 ){
				str2 = str2.charAt(0) + scrambler.randomizeStr( str2.substring( 1, str2.length - 1 ) ) + str2.charAt( str2.length - 1 );
			}
			return str2;
		});
		return str;
	},
	randomizeStr : function( str ){
		if( typeof str !== 'string' ){
			return str;
		}
		return scrambler.makeArrayRandom( str.split( '' ) ).join( '' );
	},
	makeArrayRandom : function( arr ){
		var j, x, i = arr.length;
		while( i ){
				j = parseInt(Math.random() * i, 10);
				x = arr[--i]; 
				arr[i] = arr[j];
				arr[j] = x;
		}
		return arr;
	}
};

Input:

var str = "I can't believe what I'm reading."
scrambler.scrambleStr( str );

Output: (Possible outcome)

"I can't beilvee waht I'm rndiaeg."

Try it out for yourself.
Demo: Scrambler