About reduce() function

JavaScript
#1

https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/es6/use-the-rest-parameter-with-function-parameters
const sum = (…args) => {
return args.reduce((a, b) => a + b, 0);
}

My only doubt is why do we add the ‘0’ at the end

#2

It’s initial value, think about the below. Go to the MDN maybe, there are bunch of examples.

const sum = (...args) => {
return args.reduce((a, b) => a + b, 0);
}


console.log(sum(2,3));//5


const sum1 = (...args) => {
return args.reduce((a, b) => a + b, 1);
}


console.log(sum1(2,3));//6
#3

Ok thanks :+1:
Got it!

#4

NOTE: You do not need to add the 0 to accomplish this particular task. If an initial value is not specified, the first value of the acc is the first element of the array.

#5

But this task requires 0 to solve it.
?

#6

Yup, I believe that’s because of the testcase: sum()

const sum = (...args) => {
  
  return args.reduce((a, b) => a + b);
}
console.log(sum());

/*
TypeError: Reduce of empty array with no initial value
    at Array.reduce (<anonymous>)
.......
*/
#7

@Scharnhorst89 @admit8490 You can still use reduce with an initial value of 0 if the function is written to handle the case of no arguments passed to the function.