var a=[
[1,2,3],
[1,2,3,4],
[1,2,3,4,5]
];


function compare(arr) {
var maxlen = 0; result = [];
for(var i=0; i < arr.length; i++){
if(arr[i].length > maxlen){
maxlen = arr[i].length;
}
}
for(var m=0; m < maxlen; m++){
var temp = [];
for(var n =0; n < arr.length; n++){
if(!arr[n][m]) arr[n][m]=null;
temp.push(arr[n][m]);
}
result.push(temp);
}
return result;
}
var res = compare(a);


for(var i=0; i<res.length; i++){

for(var j=0; j<res[i].length; j++){
window.document.write(res[i][j]);
if(j+1 < res[i].length){
window.document.write(",");
}

}
window.document.write("<br/>");

}