JavaScript数组如何求和

var sum = 0;

console.time("for");

for (var i = 0; i < arr.length; i++) {

    sum += arr[i];

}

console.timeEnd("for");

console.log(sum);

var sum = 0;

function getSum(item, index, array) {

    sum += item;

}

console.time();

arr.forEach(getSum);

console.timeEnd();

console.log(sum);

var sum = 0;

function getSum(item, index, array) {

    sum += item;

}

console.time();

arr.some(getSum);

console.timeEnd();

console.log(sum);

var sum = 0;

function getSum(item, index, array) {

    sum += item;

}

console.time();

arr.map(getSum);

console.timeEnd();

console.log(sum);

var sum = 0;

function getSum(item, index, array) {

    sum += item;

}

console.time();

arr.filter(getSum);

console.timeEnd();

console.log(sum);