Help me in solving JS04A problem

My issue

in my code i made a sum function with argument and in this function , used a for loop to iterate on array and every time its add in total variable and then return the total of the array value.

My code

const numbers = [10, 15, 20, 30];
/* Iterate over this array and find the total sum. */

var total = 0;

function sum(numbers) {
    for (idx=0; idx<=numbers; idx++) {
        total += numbers[idx];
    return total;

Learning course: Web development using JavaScript
Problem Link: CodeChef: Practical coding for everyone