Can somebody please help me construct a regular expression in Javascript to check if year 2017 exists or a year starting with 19 or 20 (century) exists in a given date.
My date format is : Fri Dec 01 2017 00:00:00 GMT-0800 (Pacific Standard Time).
I tried this but it fails:
var str = "Fri Dec 01 2017 00:00:00 GMT-0800 (Pacific Standard Time)";
var patt = new RegExp("/^\S{3}[\s]\S{3}[\s]\d{2}[\s]\d{4}$/");
var res = patt.test(str);
Thanks, Haseena
You can use Date.getFullYear() method.
var d = new Date("Fri Dec 01 1999 00:00:00 GMT-0800 (Pacific Standard Time)");
var year = d.getFullYear();
Date object to retrieve the year, but it's more work for the computer and completely unnecessary.
Here is example you can use.
var str="Fri Dec 01 2017 00:00:00 GMT-0800 (Pacific Standard Time)";
var patt=/(\w{3}\s){2}\d{2}\s(\d{4})\s(.*)/;
var results = patt.exec(str);
console.log(results);
console.log(results[2]);
The second group is match the year.
. and it doesn't even matter what's after the year.
The year validation with multiple condition is not quite a regex thingy
If I have understood your question then you can try this:
^[a-zA-Z]{3}\s+[A-Za-z]{3}\s+\d{2}\s+(2017|(?:19\d{2}|20\d{2}))\s+.*
const regex = /^[a-zA-Z]{3}\s+[A-Za-z]{3}\s+\d{2}\s+(2017|(?:19\d{2}|20\d{2}))\s+.*$/gm;
const str = `Fri Dec 01 2017 00:00:00 GMT-0800 (Pacific Standard Time)`;
let m;
if((m = regex.exec(str)) !== null) {
console.log("Full match ="+m[0]);
console.log("Matched year ="+m[1]);
}
else
console.log("no match found");.match and test the value using String methods? Why specify a non-capturing group when a capturing group would allow you to retrieve the full year regardless of what it is? Why use the multiline flag?
With a fixed date format, this is really easy:
First, just extract your year using a regular expression var year = str.match(/^.{11}(\d{4})/)[1]
.match returns an array where the first element is the entire matched string and subsequent elements are the parts captured in parentheses.
After you have this, you can test if year === '2017' or if year.substr(0, 2) === '19'.
There are about a dozen other ways to do this, too.
var myDate = 'Fri Dec 01 2017 00:00:00 GMT-0800 (Pacific Standard Time)';
function isCorrectYear(dateString) {
var year = dateString.match(/^.{11}(\d{4})/)[1];
if (year === '2017') return true;
}
if (isCorrectYear(myDate)) {
alert("It's the correct year.");
}Something just occurred to me... "year 2017 exists or a year starting with 19 or 20". Doesn't that cover every year in every date string you are ever likely to encounter? I don't think they had Javascript before the 1900s and I doubt anything any of us will write will still be in use after the year 2100.
var patt = /^\S{3}[\s]\S{3}[\s]\d{2}[\s]\d{4}$/;or escape backslashes in string when usingRegExpconstructor.