Previous is not defined?

When submitting, the output is stating previous is not defined. However, the challenge and the output section mentions to correct the bracket for the array and the parenthesis for the reduce function. So, I am not understanding why previous needs to be defined because that is not the challenge. If it needs to be defined, what should its’ value be? I have tried various numbers and arrays, but it is not working.

Your code so far

let myArray = [1, 2, 3];
let arraySum = myArray.reduce((previous, current => previous + current));
console.log(Sum of array values is: ${arraySum});

**Your browser information:**

User Agent is: <code>Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.102 Safari/537.36</code>.

**Link to the challenge:**

Be careful about where you’re placing your parentheses.

I was “trapped” the same way. It’s helpful to google, how reduce() is working.