JavaScript字符串indexOf无法正常工作

Question

I must be missing something .. not sure why my JavaScript is failing or not working

var discount = 10;
var newTemp;

if (discount != null) {
    if (discount.indexOf("%") > -1) {
        newTemp = discount.substring(0, 2) + '%';
    } else {
        newTemp = discount;
    }
 } //end of outer if

Above script works when discount = "10.0%" But fails when discount = 10

maynot be best way, but all I am trying to do is if discount value contains % sign then setting newTemp variable with new value. Else just keep it as is.

Any idea, why control fails when discount value is = 10

Answer 1

because "10%" is a string, therefore it has a indexOf method, and 10 is probably an integer or number.

Try discount.toString().indexOf('%')

Answer 2

It's because you're not appending the '%' in the else branch.

var newTemp;
if (discount != null) {
    if (discount.indexOf("%") > -1) {
        newTemp = discount.substring(0, 2);
    } else {
        newTemp = discount;
    }
 } //end of outer if
 newTemp += '%';

also as Hugo said, the number 10 does not have the indexOf method, which is a string method.