Format a JavaScript Date to YYYY MM DD

To format a date to YYYYMMDD in JavaScript, you can use the toLocaleDateString() function in combination with the split(), reverse(), and join() functions. The trick is that, in the UK, dates are formatted in DD/MM/YYYY format, with two digit month and day. So format the date using the en-GB locale to get two digit month and day, and then split, reverse, and join back together.

const date = new Date();

date.toLocaleDateString('en-GB').split('/').reverse().join(''); // '20211124'

Using String Concatenation

The above approach is concise, but not very readable. The en-GB trick is a bit too clever for many codebases. Here's an alternative approach that's easier to read.

const date = new Date();
const year = date.getFullYear() * 1e4; // 1e4 gives us the the other digits to be filled later, so 20210000.
const month = (date.getMonth() + 1) * 100; // months are numbered 0-11 in JavaScript, * 100 to move two digits to the left. 20210011 => 20211100
const day = date.getDate(); // 20211100 => 20211124
const result = year + month + day + '' // `+ ''` to convert to string from number, 20211124 => "20211124"

// in one line
date.getFullYear() * 1e4 + (date.getMonth() + 1) * 100 + date.getDate() + ''; // "20211124"

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