function _chunk(array, size) {
var index = 0,
resIndex = 0,
arrayLength = array.length,
length = Math.ceil(arrayLength / size),
result = Array(length)
while (index < arrayLength) {
result[resIndex++] = baseSlice(array, index, (index += size))
}
return result
}
function baseSlice(array, start, end) {
var length = array.length,
end = end > length ? length : end,
length = end - start >>> 0,
result = Array(length),
index = -1;
start >>>= 0
while (++index < length) {
result[index] = array[start + index]
}
return result
}
console.log(_chunk([1, 2, 5], 2)); //[[1,2],[5]]
>>>本质上就是保证变量有意义（为数字类型），且为正整数，在有效的数组范围内
0.1 >>> 0 返回 0
1.2 >>> 0 返回 1
-1 >>> 0 返回 4294967295
思想:算出结果数组的长度 通过baseSlice函数将数组分解成以size为数组长度的数组返回 然后通过 _chunk函数循环赋值给新数组并返回
