Rest Parameter with Function Parameters

JavaScript
1

I wanted to try the following code while examining “rest parameter” in JS. the output of the code was printed as -105. But to me, the code output is supposed to be +95. Because 100-2 = 98, 98-3 = 95. Why did this happen? Waiting for your help.

const sum = (...args) => {
return args.reduce((a, b) => a - b, 0);
}
console.log(sum(100, 2, 3));
2

I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.

See this post to find the backtick on your keyboard. The “preformatted text” tool in the editor (</>) will also add backticks around text.

Note: Backticks are not single quotes.

markdown_Forums

3

0 - 100 - 2 - 3 = -105

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4

Thank you for your warning and help.

5

When you start the args.reduce(), you set as your starting value zero (that’s the , 0) at the end of the reduce statement). Everything goes from there. The first go-round, a=0 and b=100, so 0-100 = -100. Second element, your accumulator (which will always be a in this function) a=-100 and b=2, so -100-2 = -102. And so on.

1 Like
6

thanks for your help…

7

if you don’t specify a starting value for the accumulator, that starting value will be arr[0] and would give the result you are expecting

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