Why will my reduce method not work without defining the current value at 0

Hi Zachary Davidson

If you will not provide the initial value, reduce() will execute the callback function starting at index 1, not 0. It's going to skip the first index and move on to other elements of the array.

See the below code:

const names = ['Gary', 'Pasan', 'Gabe', 'Treasure', 'Gengis', 'Gladys', 'Tony']; 

const gNames = names.reduce((sum, name) => { 

        if (name.charAt(0) === 'G') 
            { 
                    sum += 1; 
            } 
                return sum; 
});

console.log(gNames)

If you run this in the console, You will get Gary111.

You see by not giving the initial value of 0 it skipped the first index and go on to perform the condition on the remaining elements. So it Skipped Gary and return all those elements where G matches at index 0 of character which is 3.

From the docs: If no initialValue is supplied, the first element in the array will be used and skipped.

More info at MDN

Also for better readability, you can wrap your code with 3 backticks (```) on the line before and after.