Question

I tried the following code but is doesn’t work triggers an error:

val.reverse is not a function

How can I fix it?

Demo: http://jsfiddle.net/9ysZa/

//I want this output: 1,455,000
function num(val){
         var result = val.reverse().join("")
                          .match(/[0-9]{1,3}/g).join(",")
                          .match(/./g).reverse().join("");
    return result     
}
alert(num('1455000'))

Answer 1

DEMO

reverse is a method on Array.prototype—it works with arrays. Since val is a string, you’ll need to call val.split('') to get it into an array.

function num(val){
         var result = val.split('').reverse().join("")
                          .match(/[0-9]{1,3}/g).join(",")
                          .match(/./g).reverse().join("");
    return result     
}
alert(num('1455000'));

Which alerts the results you’re looking for.

EDIT

Based on your comment, it looks like you want to run this on the number 1455000 rather than the string ‘1455000’. If so, adding a toString call before split() will work (and will work on both strings **and numbers).

Here’s an updated fiddle