javascript将10进制数转换为2进制

var num = 11;
var str = num.toString(2);

/*将十进制数转变为二进制数*/
function dec2bin(num){
var result = "";
if(num == 0){
return "0";
}
while(num > 0){
result = num % 2 + result;
num = parseInt(num / 2 , 10);
}
return result;
}