在Javascript中一次按一组4个元素循环遍历数组？

Question

I have an long list of number array and I want to loop through the array by 4 elements at a time

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

I want to loop through them so I can work with 1-4 , 5-8 , 9-12 like that

Answer 1

Use a for loop where i increases by 4.

Note: I was working on my answer when Jaromanda X commented the same thing.

 var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]; for (var i = 0; i < arr.length; i += 4) { console.log("Working with: " + arr.slice(i, i + 4)); }

Answer 2

Using ES6 and array functions:

 const arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]; [...Array(Math.ceil(arr.length / 4)).keys()].forEach(i => { const [a, b, c, d] = arr.slice(i * 4, (i+1) * 4) // a, b, c and d are the four elements of this iteration console.log(`iteration n°${i}`, a, b, c, d) })

Notice: Math.ceil is used to prevent any error if the array length is not divisible by 4

Answer 3

The lodash chunk method does that.

_.chunk(['a', 'b', 'c', 'd'], 2);
// => [['a', 'b'], ['c', 'd']]

_.chunk(['a', 'b', 'c', 'd'], 3);
// => [['a', 'b', 'c'], ['d']]