Tell us what’s happening:
Your code so far
const sum = (...args) => {
return args.reduce((a, b) => a + b, 0);
}
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User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36.
Challenge: Use the Rest Parameter with Function Parameters
Link to the challenge:
My question is why did we use 0 in the arrow function ??
return args.reduce((a, b) => a + b, 0);
Hi @junaidshaikh_js!
I have added spoiler tags around your code for those who have not worked on this problem yet.
The 0 in this case represents the initial value for the accumulator parameter, which is a.
The initial value is techinally optional.
MDN answer
A value to use as the first argument to the first call of the callback . If no initialValue is supplied, the first element in the array will be used as the initial accumulator value and skipped as currentValue .
Here is a screenshot of what the code looks like in a debugger with the accumulator set to 0 (take a look at the left side of the pic)
Here is a screenshot of what the code looks like without the initial value
Hope that makes sense.
