Date Utilities in JavaScript

1// Method 1: Get start/end of day
2function startOfDay(date) {
3    const d = new Date(date);
4    d.setHours(0, 0, 0, 0);
5    return d;
6}
7
8function endOfDay(date) {
9    const d = new Date(date);
10    d.setHours(23, 59, 59, 999);
11    return d;
12}
13
14const today = new Date();
15console.log('Start of day:', startOfDay(today));
16console.log('End of day:', endOfDay(today));
17
18// Method 2: Get start/end of week
19function startOfWeek(date) {
20    const d = new Date(date);
21    const day = d.getDay();
22    const diff = d.getDate() - day;
23    return new Date(d.setDate(diff));
24}
25
26function endOfWeek(date) {
27    const start = startOfWeek(date);
28    return new Date(start.getTime() + 6 * 24 * 60 * 60 * 1000);
29}
30
31console.log('Start of week:', startOfWeek(today));
32console.log('End of week:', endOfWeek(today));
33
34// Method 3: Get start/end of month
35function startOfMonth(date) {
36    return new Date(date.getFullYear(), date.getMonth(), 1);
37}
38
39function endOfMonth(date) {
40    return new Date(date.getFullYear(), date.getMonth() + 1, 0);
41}
42
43console.log('Start of month:', startOfMonth(today));
44console.log('End of month:', endOfMonth(today));
45
46// Method 4: Get start/end of year
47function startOfYear(date) {
48    return new Date(date.getFullYear(), 0, 1);
49}
50
51function endOfYear(date) {
52    return new Date(date.getFullYear(), 11, 31);
53}
54
55console.log('Start of year:', startOfYear(today));
56console.log('End of year:', endOfYear(today));
57
58// Method 5: Days in month
59function daysInMonth(date) {
60    return new Date(date.getFullYear(), date.getMonth() + 1, 0).getDate();
61}
62
63console.log('Days in month:', daysInMonth(today));
64
65// Method 6: Is leap year
66function isLeapYear(year) {
67    return (year % 4 === 0 && year % 100 !== 0) || (year % 400 === 0);
68}
69
70console.log('Is leap year:', isLeapYear(2024));
71
72// Method 7: Get day name
73function getDayName(date, locale = 'en-US') {
74    return date.toLocaleDateString(locale, { weekday: 'long' });
75}
76
77console.log('Day name:', getDayName(today));
78
79// Method 8: Get month name
80function getMonthName(date, locale = 'en-US') {
81    return date.toLocaleDateString(locale, { month: 'long' });
82}
83
84console.log('Month name:', getMonthName(today));
85
86// Method 9: Is weekend
87function isWeekend(date) {
88    const day = date.getDay();
89    return day === 0 || day === 6;
90}
91
92console.log('Is weekend:', isWeekend(today));
93
94// Method 10: Is weekday
95function isWeekday(date) {
96    return !isWeekend(date);
97}
98
99console.log('Is weekday:', isWeekday(today));