JavaScript Dates
Getters read each part of a date, and setters change them.
Each part has both a local and a UTC version.
Mixing the two is a reliable source of off-by-one-day bugs.
Example
javascript
const date = new Date(Date.UTC(2026, 0, 15, 14, 30, 45));
console.log(date.getUTCFullYear());
console.log(date.getUTCHours());
console.log(date.getUTCMinutes());The output is 2026, 14, 30.
getFullYear, getMonth, getDate for the date.
getHours, getMinutes, getSeconds for the time.
getDay gives the weekday, where 0 is Sunday.
Syntax
javascript
date.getFullYear();
date.getUTCFullYear();Pick local or UTC and use it consistently.
getDate is the day of the month.
getDay is the day of the week.
Example
javascript
const date = new Date(Date.UTC(2026, 0, 15));
console.log(date.getUTCDate());
console.log(date.getUTCDay());The names are unhelpfully similar, so read carefully.
An array turns the number into a name.
Example
javascript
const names = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
const date = new Date(Date.UTC(2026, 0, 15));
console.log(names[date.getUTCDay()]);toLocaleDateString does this properly for other languages.
getYear is an ancient method that returns the year minus 1900.
Always use getFullYear.
Example
javascript
const date = new Date(Date.UTC(2026, 0, 15));
console.log(date.getUTCFullYear());
console.log(date.getUTCFullYear() === 2026);The old method still exists, which is why the mistake persists.
Each getter has a matching setter that changes the date in place.
Example
javascript
const date = new Date(Date.UTC(2026, 0, 15));
date.setUTCFullYear(2027);
date.setUTCMonth(5);
console.log(date.getUTCFullYear());
console.log(date.getUTCMonth());The output is 2027 then 5.
Padding keeps the display steady.
Example
javascript
const date = new Date(Date.UTC(2026, 0, 15, 9, 5));
const time = String(date.getUTCHours()).padStart(2, "0") + ":" +
String(date.getUTCMinutes()).padStart(2, "0");
console.log(time);The output is 09:05.
Complete Example
html
<!DOCTYPE html>
<html>
<head>
<title>JavaScript Date Components</title>
</head>
<body>
<h1>Date Components</h1>
<p id="out"></p>
<script>
const names = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
const date = new Date(Date.UTC(2026, 0, 15, 9, 5));
document.getElementById("out").innerHTML =
"Year: " + date.getUTCFullYear() +
"<br>Day of month: " + date.getUTCDate() +
"<br>Weekday: " + names[date.getUTCDay()] +
"<br>Time: " + String(date.getUTCHours()).padStart(2, "0") +
":" + String(date.getUTCMinutes()).padStart(2, "0");
</script>
</body>
</html>Run the above example in the Try It Editor.
Try another date:
Change the day and watch the weekday name change.
getDate is the day of the month.getDay is the day of the week, starting at Sunday.getFullYear.The getters are straightforward once getDay and getDate are clear.
Sticking to either local or UTC throughout avoids off-by-one bugs.
For display, the locale formatters are better than building strings yourself.