我需要将一个 JavaScript 数组拆分成一定n大小的块。
例如：给定这个数组
["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"]
an等于4，输出应该是这样的：
[ ["a1", "a2", "a3", "a4"],
["a5", "a6", "a7", "a8"],
["a9", "a10", "a11", "a12"],
["a13"]
]
我知道针对这个问题的纯 JavaScript解决方案，但由于我已经在使用Lodash，我想知道 Lodash 是否为此提供了更好的解决方案。
我创建了一个jsPerf 测试来检查下划线解决方案的速度有多慢。
看看 lodash 的块：https : //lodash.com/docs#chunk
const data = ["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"];
const chunks = _.chunk(data, 3);
console.log(chunks);
// [
// ["a1", "a2", "a3"],
// ["a4", "a5", "a6"],
// ["a7", "a8", "a9"],
// ["a10", "a11", "a12"],
// ["a13"]
// ]<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>对于基于下划线的解决方案，试试这个：
var data = ["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"];
var n = 3;
var lists = _.groupBy(data, function(element, index){
return Math.floor(index/n);
});
lists = _.toArray(lists); //Added this to convert the returned object to an array.
console.log(lists);
使用链包装器方法，您可以将两个语句组合如下：
var data = ["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"];
var n = 3;
var lists = _.chain(data).groupBy(function(element, index){
return Math.floor(index/n);
}).toArray()
.value();
一个可能更简单的表达：
const coll = [ "a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9" ];
const n = 2;
const chunks = _.range(coll.length / n).map(i => coll.slice(i * n, (i + 1) * n));
console.log(chunks);<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>Underscore从版本 1.9.0 开始支持_.chunk()。
const data = ["a1", "a2", "a3", "a4", "a5", "a6", "a7", "a8", "a9", "a10", "a11", "a12", "a13"];
const chunks = _.chunk(data, 4);
console.log(chunks);<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore.js"></script>试试这个更实用（例如，如果您想根据要在每个子数组中作为容器的项目数量来拆分数组）：
function chunk(arr, start, amount){
var result = [],
i,
start = start || 0,
amount = amount || 500,
len = arr.length;
do {
//console.log('appending ', start, '-', start + amount, 'of ', len, '.');
result.push(arr.slice(start, start+amount));
start += amount;
} while (start< len);
return result;
};
以及在您的情况下的使用：
var arr = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17],
chunked = chunk(arr, 0, Math.floor(arr.length/3)); //to get 4 nested arrays
console.log(chunked);
还有一个案例：
var arr = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17],
chunked = chunk(arr, 0, 3); // to get 6 nested arrays each containing maximum of 3 items
console.log(chunked);