How to optimize the sum of the elements of an array

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How to optimize the sum of the elements of an array

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#1 by (10 votes)
#2 by (8 votes)
#3 by (5 votes)

8

I need to get the value of the sum of the items of a array in JavaScript.

The amount of these items can easily reach 2,000 items. Items are of type int , no testing required.

ar = [1,3,5,...,2000];

I already have a array containing the elements, I do not need to get the value in the inputs . I want to add the elements of this array , in a clear and objective way.

Is this correct? Will I lose by tying?

for (f=0;f<60;f++)
{
  valorSoma = ar[f]+valorSoma;
}

javascript desempenho array

asked by anonymous 27.10.2016 / 18:07

3 answers

8

From ES6, you can use Array.reduce with arrow functions :

var numeros = [1, 3, 4, 2000];
var soma = numeros.reduce((a, b) => a + b);

console.log(soma);

Another alternative with while :

var numeros = [1, 3, 4, 2000];
var tamanho = numeros.length;
var total = 0;

while(tamanho--) {
  total += numeros[tamanho];
}

console.log(total);

27.10.2016 / 18:55

5

Use reduce

var meuArray = [1, 2, 3, 200];

var countArray = meuArray.reduce(function(total, item) {
    return total+item;
}, 0);

alert(countArray);

See how it works in W3schools , and a great video to learn that too funfunfunction

27.10.2016 / 18:14

Property readonly .NET Is it correct to write CSS with Javascript?

score 10 · Accepted Answer

If you want the most performative way:

var ar = [1,3,5,8,2000];
for (var i = 0, total = 0; i < ar.length; total += ar[i++]);
console.log(total);

My result by comparing for , for with length external (contrary to popular belief is slower than leaving internal), reduce() and forEach() :

So your way is correct, even though you're only getting 60 items and not writing as well as you can. I made the shortest possible (since the comparison seems to be using a ready function) without losing performance.