isLeapYear

Version where year is given as a Date object.

by denvdmj

JavaScript

const isLeapYear = date =>
	(year => !(year % 4) && !!(year % 100) || !(year % 400)) (date.getFullYear());

// TEST
// http://calendarin.net/old/leap-years.php
const leapYearsList = [
  1972,
  1976,
  1980,
  1984,
  1988,
  1992,
  1996,
  2000,
  2004,
  2008,
  2012,
  2016,
  2020,
  2024,
  2028,
  2032,
  2036,
  2040,
  2044,
  2048,
  2052,
  2056,
  2060,
  2064,
  2068,
  2072,
  2076,
  2080,
  2084,
  2088,
  2092,
  2096,
  2104,
  2108,
  2112,
  2116,
  2120,
  2124,
  2128,
  2132,
  2136,
  2140,
  2144,
  2148,
  2152,
  2156,
  2160,
  2164,
  2168,
  2172,
  2176,
  2180,
  2184,
  2188,
  2192,
  2196,
  2204,
  2208,
  2212,
  2216,
  2220,
  2224,
  2228,
  2232,
  2236,
  2240,
  2244,
  2248,
  2252,
  2256,
  2260,
  2264,
  2268,
  2272,
  2276,
  2280,
  2284,
  2288,
  2292,
  2296,
  2304,
  2308,
  2312,
  2316,
  2320,
  2324,
  2328,
  2332,
  2336,
  2340,
  2344,
  2348,
  2352,
  2356,
  2360,
  2364,
  2368,
  2372,
  2376,
  2380,
  2384,
  2388,
  2392,
  2396,
  2400,
  2404,
  2408,
  2412,
  2416,
  2420,
  2424,
  2428,
  2432,
  2436,
  2440,
  2444,
  2448,
  2452,
  2456,
  2460,
  2464,
  2468,
  2472,
  2476,
  2480,
  2484,
  2488,
  2492,
  2496,
  2504,
  2508,
  2512,
  2516,
  2520,
  2524,
  2528,
  2532,
  2536,
  2540,
  2544,
  2548,
  2552,
  2556,
  2560,
  2564,
  2568,
  2572,
  2576,
  2580,
  2584,
  2588,
  2592,
  2596,
  2604,
  2608,
  2612,
  2616,
  2620,
  2624,
  2628,
  2632,
  2636,
  2640,
  2644,
  2648,
  2652,
  2656,
  2660,
  2664,
  2668,
  2672,
  2676,
  2680,
  2684,
  2688,
  2692,
  2696,
  2704,
  2708,
  2712,
  2716,
  2720,
  2724,
  2728,
  2732,
  2736,
  2740,
  2744,
  2748,
  2752,
  2756,
  2760,
  2764,
  2768,
  2772,
  2776,
  2780,
  2784,
  2788,
  2792,
  2796,
  2800,
  2804,
  2808,
  2812,
  2816,
  2820,
  2824,
  2828,
  2832,
  2836,
  2840,
  2844,
  2848,
  2852,
  2856,
  2860,
  2864,
  2868,
  2872,
  2876,
  2880,
  2884,
  2888,
  2892,
  2896,
 ...