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File size: 872 Bytes
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function length(array) {
return array.length | 0;
}
function empty(length) {
return !(length > 0);
}
function arrayify(values) {
return typeof values !== "object" || "length" in values ? values : Array.from(values);
}
function reducer(reduce) {
return values => reduce(...values);
}
export default function cross(...values) {
const reduce = typeof values[values.length - 1] === "function" && reducer(values.pop());
values = values.map(arrayify);
const lengths = values.map(length);
const j = values.length - 1;
const index = new Array(j + 1).fill(0);
const product = [];
if (j < 0 || lengths.some(empty)) return product;
while (true) {
product.push(index.map((j, i) => values[i][j]));
let i = j;
while (++index[i] === lengths[i]) {
if (i === 0) return reduce ? product.map(reduce) : product;
index[i--] = 0;
}
}
}
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