locutus/haskell/list/intercalate.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.intercalate = intercalate;
function intercalate(separator, lists) {
    //  discuss at: https://locutus.io/haskell/list/intercalate/
    // original by: Kevin van Zonneveld (https://kvz.io)
    //      note 1: Concatenates lists with separator inserted between sublists, like Haskell Data.List.intercalate.
    //   example 1: intercalate([0], [[1, 2], [3], [4, 5]])
    //   returns 1: [1, 2, 0, 3, 0, 4, 5]
    //   example 2: intercalate([' '], [['a'], ['b'], ['c']])
    //   returns 2: ['a', ' ', 'b', ' ', 'c']
    //   example 3: intercalate([], [[1], [2]])
    //   returns 3: [1, 2]
    if (!Array.isArray(separator) || !Array.isArray(lists) || lists.length === 0) {
        return [];
    }
    const out = [];
    for (let i = 0; i < lists.length; i++) {
        const chunk = lists[i];
        if (Array.isArray(chunk)) {
            out.push(...chunk);
        }
        if (i < lists.length - 1) {
            out.push(...separator);
        }
    }
    return out;
}