Kid Projects

Encoding and Decoding

Type in a message into the encode box to have it get encoded, or into the decode to get it decoded.
The number is used in the encoding and decoding code.
Please only lowercase letters, and no spaces or punctuation.
Keep in mind that the length of your encoded message is the number
you enter plus that of your message. Enjoy!

number

encode

encode

decode

decode

Summary

What the program does is it makes number number of random numbers and stores it in an array.
Then it takes the message and offsets each letter in the message by the number that it
would be next to if you were to lay out the message under repeating copies of the array.
Then it puts the key at the beggining of the message.

The Code

This is the javascript code that is inside this html document.
The 'document.getElementById' line's get the information you have typed into the boxes and write out the results to the text elements.

var random5 = function () {
    var a = [];
    var number = document.getElementById("number").value;
    for(var i=0; i < number; i++){
        a.push(parseInt(26.5*Math.random()));
    }
    return a;
};
var converttoletter = function(num) {
    if (num===1) {return "a";}
    else if (num===2) {return "b";}
    else if (num===3) {return "c";}
    else if (num===4) {return "d";}
    else if (num===5) {return "e";}
    else if (num===6) {return "f";}
    else if (num===7) {return "g";}
    else if (num===8) {return "h";}
    else if (num===9) {return "i";}
    else if (num===10) {return "j";}
    else if (num===11) {return "k";}
    else if (num===12) {return "l";}
    else if (num===13) {return "m";}
    else if (num===14) {return "n";}
    else if (num===15) {return "o";}
    else if (num===16) {return "p";}
    else if (num===17) {return "q";}
    else if (num===18) {return "r";}
    else if (num===19) {return "s";}
    else if (num===20) {return "t";}
    else if (num===21) {return "u";}
    else if (num===22) {return "v";}
    else if (num===23) {return "w";}
    else if (num===24) {return "x";}
    else if (num===25) {return "y";}
    else if (num===26) {return "z";}
    else {return 'X'}
};
var converttonumber = function (lett) {
    if (lett==="a") {return 1}
    else if (lett==="b") {return 2;}
    else if (lett==="c") {return 3;}
    else if (lett==="d") {return 4;}
    else if (lett==="e") {return 5;}
    else if (lett==="f") {return 6;}
    else if (lett==="g") {return 7;}
    else if (lett==="h") {return 8;}
    else if (lett==="i") {return 9;}
    else if (lett==="j") {return 10;}
    else if (lett==="k") {return 11;}
    else if (lett==="l") {return 12;}
    else if (lett==="m") {return 13;}
    else if (lett==="n") {return 14;}
    else if (lett==="o") {return 15;}
    else if (lett==="p") {return 16;}
    else if (lett==="q") {return 17;}
    else if (lett==="r") {return 18;}
    else if (lett==="s") {return 19;}
    else if (lett==="t") {return 20;}
    else if (lett==='u') {return 21;}
    else if (lett==='v') {return 22;}
    else if (lett==='w') {return 23;}
    else if (lett==='x') {return 24;}
    else if (lett==='y') {return 25;}
    else if (lett==='z') {return 26;}
    else {return 0}
};
var constringtoarray = function (string){
    var arra = [];
    for(var i = 0; i < string.length; i++){
        arra[i] = string[i];   
    }
    
    return arra;
};
var conarraytostring = function (arra){
    var mystring = '';
    for(var i = 0; i < arra.length; i++){
        mystring=mystring+arra[i];    
    }
    return mystring;
};

var encode1 = function () {
    var number = document.getElementById("number").value;
    var arra = random5();
    var message = document.getElementById("messegeforencoding").value;
    message = constringtoarray(message.toLowerCase());
    
    for(var i = 0; i < message.length; i++){
        if (converttonumber(message[i]) + arra[i%number]>26) {
            message[i] = converttoletter(converttonumber(message[i]) + arra[i%number] - 26);
        }else {
            message[i] = converttoletter(converttonumber(message[i]) + arra[i%number]);
        }
    }
    for(var i=0; i < arra.length; i++){
	arra[i] = converttoletter(arra[i]);
    }
    document.getElementById("encoded").textContent = conarraytostring(arra.concat(message))
};

var decode1 = function (){
    var number = document.getElementById("number").value;
    var key = [];
    var decodeme = [];
    var messege = document.getElementById("messegefordecoding").value;
    constringtoarray(messege);

    for(var i = 0; i < number; i++){
        key[i]=converttonumber(messege[i]);
    }
 
    for(var i = number; i < messege.length; i++){
	if (converttonumber(messege[i]) - key[i%number]===0){
	    decodeme[i-number] = 'X';
        }else if (converttonumber(messege[i]) - key[i%number]<1){
            decodeme[i-number] = converttoletter(converttonumber(messege[i]) - key[(i)%number]+26);
        }else{
            decodeme[i-number] = converttoletter(converttonumber(messege[i]) - key[(i)%number]);
        }
        
    }
    document.getElementById("decoded").textContent = conarraytostring(decodeme);
};