Javascript - Counting array elements by reduce method until specific value occurs doesn't give a correct output

Question

const arr = [5,6,0,7,8];
const sum = (arr,num) => arr.reduce((total)=>(num==0 ? total : total+num), 0) 
console.log(sum(arr, 0))

Please check how

Answer 1

You need parenthesis to execute the function ()

sum(arr, 0)

Without parenthesis you store a reference to the function in the variable