const regex = /(?<=\D|^)(?<year>\d{4})(?<sep>[^\w\s])(?<month>1[0-2]|0[1-9])\k<sep>(?<day>0[1-9]|[12][0-9]|(?<=11\k<sep>|[^1][4-9]\k<sep>)30|(?<=1[02]\k<sep>|[^1][13578]\k<sep>)3[01])(?=\D|$)/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('(?<=\\D|^)(?<year>\\d{4})(?<sep>[^\\w\\s])(?<month>1[0-2]|0[1-9])\\k<sep>(?<day>0[1-9]|[12][0-9]|(?<=11\\k<sep>|[^1][4-9]\\k<sep>)30|(?<=1[02]\\k<sep>|[^1][13578]\\k<sep>)3[01])(?=\\D|$)', 'gm')
const str = `
2020-01-01
2020-01-31
2020-02-29
2020-03-31
2020-04-30
2020-05-31
2020-06-30
2020-07-31
2020-08-31
2020-09-30
2020-10-31
2020-11-30
2020-12-31
2020-01-01 00:00:00,000
2020-01-01_00:00:00,000
2020-01-01-00:00:00,000
2020-01-01T00:00:00,000
2222-01-01
2222/11/22
2222.11.22
// Invalid dates
2020-00-01
2020-01-00
000-01-01
222-01-01
2020-1-1
2020-1-01
2020-01-1
2020-22-01
2020-01-33
2020-01-32
2020-02-30
2020-03-32
2020-04-31
2020-05-32
2020-06-31
2020-07-32
2020-08-32
2020-09-31
2020-10-32
2020-11-31
2020-12-32
a222-01-01
2a22-01-01
22a2-01-01
222a-01-01
2222-a1-01
2222-0a-01
2222-1a-01
2222-01-a1
2222-01-0a
2222-01-1a`;
// Reset `lastIndex` if this regex is defined globally
// regex.lastIndex = 0;
let m;
while ((m = regex.exec(str)) !== null) {
// This is necessary to avoid infinite loops with zero-width matches
if (m.index === regex.lastIndex) {
regex.lastIndex++;
}
// The result can be accessed through the `m`-variable.
m.forEach((match, groupIndex) => {
console.log(`Found match, group ${groupIndex}: ${match}`);
});
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions