Fastest JavaScript summation

Question

What is the fastest way to sum up an array in JavaScript? A quick search turns over a few different methods, but I would like a native solution if possible. This will run un

Answer 1

I tried using performance.now() to analyze the performance of the different types of loops. I took a very large array and found the sum of all elements of the array. I ran the code three times every time and found forEach and reduce to be a clear winner.

// For loop

let arr = [...Array(100000).keys()]
function addUsingForLoop(ar){
  let sum = 0;
  for(let i = 0; i < ar.length; i++){
    sum += ar[i];
  }
   console.log(`Sum: ${sum}`);
   return sum;
}
let t1 = performance.now();
addUsingForLoop(arr);
let t2 = performance.now();
console.log(`Time Taken ~ ${(t2 - t1)} milliseconds`)

// "Sum: 4999950000"
// "Time Taken ~ 42.17500000959262 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 44.41999999107793 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 49.845000030472875 milliseconds"

// While loop

let arr = [...Array(100000).keys()]
function addUsingWhileLoop(ar){
let sum = 0;
let index = 0;
while (index < ar.length) {
  sum += ar[index];
  index++;
}
  console.log(`Sum: ${sum}`)
  return sum;
}
let t1 = performance.now();
addUsingWhileLoop(arr);
let t2 = performance.now();
console.log(`Time Taken ~ ${(t2 - t1)} milliseconds`)

// "Sum: 4999950000"
// "Time Taken ~ 44.2499999771826 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 44.01999997207895 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 41.71000001952052 milliseconds"

// do-while

let arr = [...Array(100000).keys()]
function addUsingDoWhileLoop(ar){
let sum = 0;
let index = 0;
do {
   sum += index;
   index++;
} while (index < ar.length);
   console.log(`Sum: ${sum}`);
   return sum;
}
let t1 = performance.now();
addUsingDoWhileLoop(arr);
let t2 = performance.now();
console.log(`Time Taken ~ ${(t2 - t1)} milliseconds`)

// "Sum: 4999950000"
// "Time Taken ~ 43.79500000504777 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 43.47500001313165 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 47.535000019706786 milliseconds"

// Reverse loop

let arr = [...Array(100000).keys()]
function addUsingReverseLoop(ar){
   var sum=0;
   for (var i=ar.length; i--;) {
     sum+=arr[i];
   }
   console.log(`Sum: ${sum}`);
   return sum;
}
let t1 = performance.now();
addUsingReverseLoop(arr);
let t2 = performance.now();
console.log(`Time Taken ~ ${(t2 - t1)} milliseconds`)

// "Sum: 4999950000"
// "Time Taken ~ 46.199999982491136 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 44.96500000823289 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 43.880000011995435 milliseconds"

// Reverse while loop

let arr = [...Array(100000).keys()]
function addUsingReverseWhileLoop(ar){
    var sum = 0;
    var i = ar.length; 
    while (i--) {
        sum += ar[i];
    }
    console.log(`Sum: ${sum}`);
    return sum;
}
var t1 = performance.now();
addUsingReverseWhileLoop(arr);
var t2 = performance.now();
console.log(`Time Taken ~ ${(t2 - t1)} milliseconds`)

// "Sum: 4999950000"
// "Time Taken ~ 46.26999999163672 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 42.97000000951812 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 44.31500000646338 milliseconds"

// reduce

let arr = [...Array(100000).keys()]
let t1 = performance.now();
sum = arr.reduce((pv, cv) => pv + cv, 0);
console.log(`Sum: ${sum}`)
let t2 = performance.now();
console.log(`Time Taken ~ ${(t2 - t1)} milliseconds`)

// "Sum: 4999950000"
// "Time Taken ~ 4.654999997001141 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 5.040000018198043 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 4.835000028833747 milliseconds"

// forEach

let arr = [...Array(100000).keys()]
function addUsingForEach(ar){
  let sum = 0;
  ar.forEach(item => {
    sum += item;
  })
    console.log(`Sum: ${sum}`);
    return sum
}
let t1 = performance.now();
addUsingForEach(arr)
let t2 = performance.now();
console.log(`Time Taken ~ ${(t2 - t1)} milliseconds`)

// "Sum: 4999950000"
// "Time Taken ~ 5.315000016707927 milliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 5.869999993592501 mienter code herelliseconds"
// "Sum: 4999950000"
// "Time Taken ~ 5.405000003520399 milliseconds"