We check if a date has the MM/DD/YYYY format with JavaScript with the test method.
For instance, we can write:
const dateRegex = /^(0\[1-9]|1\[0-2\])\/(0\[1-9]|1\d|2\\d|3\[01])\/(19|20)\d{2}$/;
console.log(dateRegex.test('2021-10-01'))
console.log(dateRegex.test('10/01/2021'))
We have the dateRegex regex that checks if a string is in the MM/DD/YYYY format.
The pattern (0[1–9]|1[0–2]) checks if the first number is between 01 and 12.
The pattern (0[1–9]|1\d|2\d|3[01]) checks if the second number is between 01 and 31.
And (19|20)\d{2} checks if the 3rd number starts with 19 or 20 and ends with 2 digits.
\/ checks whether slashes are between the numbers.
Therefore, the first console log is false and the 2nd one logs true .
