How to find the sum of a set of numbers

Question

Given an array [1,2,3,4], how to find the sum of its elements? (In this case, the sum would be 10.) I think $.each might work, but I'm not sure how to implement it.

P粉681400307 · Answer

That's exactly what does to reduce .

If you are using ECMAScript 2015 (aka ECMAScript 6):

const sum = [1, 2, 3].reduce((partialSum, a) => partialSum + a, 0);
console.log(sum); // 6

For older JS:

const sum = [1, 2, 3].reduce(add, 0); // with initial value to avoid when the array is empty

function add(accumulator, a) {
  return accumulator + a;
}

console.log(sum); // 6

Isn’t this beautiful? :-)

P粉952365143 · Answer

Recommended (reduce by default)

Array.prototype.reduce Can be used to iterate over an array, adding the current element value to the sum of previous element values.

console.log(
  [1, 2, 3, 4].reduce((a, b) => a + b, 0)
)
console.log(
  [].reduce((a, b) => a + b, 0)
)