Naturally distort text

gistfile1.js

/*

If a character is distorted, it will be replaced with an adjacent key on the keyboard.
The probability that a character will be distorted is determined by the function.

HOW TO USE:
Open a new tab and type about:blank in the address bar, press enter
Right click and choose 'Inspect Element'
Choose the 'Console' tab
Paste all of this in and press enter

*/

var kybdMatrix = ['qwertyuiop','asdfghjkl;','zxcvbnm,./'];

//(p*100) percent chance of distorting character c
function distortChar(c, p){
    var r = Math.random();

    if(r <= p){
        //Distort this character
        //Find character in keyboard matrix
        for(var kybdRow = 0; kybdRow < kybdMatrix.length; kybdRow++){
            var kybdCol = kybdMatrix[kybdRow].indexOf(c);
            if(kybdCol > -1){
                //kybdRow and kybdCol are correct
                var r2 = Math.random();
                var r3 = Math.random();
                if(r2 > .5){
                    //Down or up
                    if(kybdRow == 0 || (r3 > .5 && kybdRow != kybdMatrix.length-1)){
                        //Down
                        kybdRow++;
                    } else {
                        //Up
                        kybdRow--;
                    }
                } else {
                    //Right oar left
                    if(kybdCol == 0 || (r3 > .5 && kybdCol != kybdMatrix[0].length-1)){
                        //Right
                        kybdCol++;
                    } else {
                        //Left
                        kybdCol--;
                    }
                }
                return kybdMatrix[kybdRow][kybdCol];
            }
        }
        return c;
    } else {
        return c;
    }
}

function distortByFunction(string, fn){
    if(fn == null){
        fn = squared;
    }

    //Scaled x value. If string has 5 characters, the x values will be 0, .2, .4, .6, and .8
    var xScale = 1 / string.length;

    var distortedStr = '';

    for(var i=0; i<string.length; i++){
        var p = fn(xScale * i);
        distortedStr += distortChar(string[i], p);
    }

    return distortedStr;
}

var distFns = {
    constant: function(x){
        return 50;
    },
    linear: function(x){
        return x;
    },
    squared: function(x){
        return Math.pow(x,2);
    },
    reverseSquared: function(x){
        return 1 - Math.pow(x,.5);
    }
};

var textToDistort = prompt('Enter text to distort');
var distFnName = prompt('Enter a distortion function (constant, linear, squared, or reverseSquared) or leave blank for squared');
var distFn;
if(distFns[distFn]){
    distFn = distFns[distFn];
} else {
    distFn = distFns['squared'];
}
alert(distortByFunction(textToDistort,distFn));