Applies fn
to each value in arr
, splitting it each time fn
returns a new value.
Use Array.prototype.reduce()
with an accumulator object that will hold the resulting array and the last value returned from fn
.
Use Array.prototype.push()
to add each value in arr
to the appropriate partition in the accumulator array.
代码片段
const partitionBy = (arr, fn) =>
arr.reduce(
({ res, last }, v, i, a) => {
const next = fn(v, i, a);
if (next !== last) res.push([v]);
else res[res.length - 1].push(v);
return { res, last: next };
},
{ res: [] }
).res;
使用样例
const numbers = [1, 1, 3, 3, 4, 5, 5, 5];
partitionBy(numbers, n => n % 2 === 0); // [[1, 1, 3, 3], [4], [5, 5, 5]]
partitionBy(numbers, n => n); // [[1, 1], [3, 3], [4], [5, 5, 5]]