Math.max Function in Javascript

Question

I have this simple issue that I can't figure out trying to find out the max from a string, yes it is a string, converting to a float. According to JS it can take an array... but everytime I try to find the max it is just printing the first value. In this case 13... not sure why? The expected result is 30.

Please help. Thanks!

function myFunction() {
 var str = "13, 24, 30, 4";//30
 var res = str.split(",");
 var max = Math.max(parseFloat(res));
 document.getElementById("demo").innerHTML = res+ " " + max;//test
 }

• Bergi: res is an array. parseFloat takes a string. Math.max does not take an array, but multiple arguments.
• Marvin Smit: Take a look at Bergi's answer. Pay special attention to how he's using the "apply" on the Math.max function.
• jeffr: I will try to test this out. I have actually found a solution myself a couple of hours later. It does help to find some expert or experienced opinions. Thanks a bunch!

Answer 1

res is an array. parseFloat takes a string. Math.max does not take an array, but multiple arguments. Notice that you don't even need parseFloat, as Math.max casts its arguments to numbers anyway. So you have to use apply to get the array into Math.max:

var str = "13, 24, 30, 4";
var max = Math.max.apply(Math, str.split(", "));
document.getElementById("demo").innerHTML = "max("+res+") = "+max;

• jeffr: Oh sorry Bergi! Thanks! I didn't know that's how to do it in here such a noob.