const regex = /.*[^\d](19|20)\d{2}(0[1-9]|1[0-2])(0[1-9]|[12]\d|3[01])$/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('.*[^\\d](19|20)\\d{2}(0[1-9]|1[0-2])(0[1-9]|[12]\\d|3[01])$', 'gm')
const str = `fileNamePrefix_20171219
fileNamePrefix_20170019
fileNamePrefix_20171200
fileNamePrefix_19631219
fileNamePrefix_18631219
fileNamePrefix_20171319
fileNamePrefix_20171240
fileNamePrefix_20171219131415111`;
// 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