Which do you like more smallest script of 2 padLeft functions?

padleft.small.js

function pad1(str,char,loop){
    var result = '';
    for(var i=0;i<loop;i++) result+=char;
    return (result+str).slice(-loop);
}
function pad2(str,char,loop){
    for(var i=0,len=loop-str.length;i<len;i++) 
        str = char + str;
    return str;
}
alert(pad1('12','0',4));
alert(pad2('12','0',4));