正则表达式以数字形式查找年份

Question

I'm trying to find a valid year between 1900 and now in strings like this: 5050.2011.DVD.XviD.AVI.117715.imported

I'm looking for 4 digits that aren't surrounded by other digits and start with 19 or 20.

So far this is what I have, but the expression returns 2011,20.

/(?!=\d)(19|20)[0-9][0-9](?!\d)/

How do I fix this?

Answer 1

Use split >>

s.split(/[^\d]/).filter(function(n){if((n>=1900)&&(n<=2099))return n})​

Check this demo .

Answer 2

This regex would return all the years between 1900-2099.

[^0-9](19|20)[0-9]{2}[^0-9]

Now, run another regex on the above returned results:

(19|20)[0-9]{2}

To explain you what's happening, first regex weeds out all the un-needed characters, and returns a string like .2012. .

And the second regex extracts the year from .2012. and returns 2012 .

---

But if you want to be specific, every 10 years, you'll have to update the regex yourself:

[^0-9]((19[0-9]{2})|(20[0-1][0-9]))[^0-9]

See the second last [0-1] in the regex? This is what you'll have to update every 10 years to the second last digit of the currect year.

For example, if it was 2023, you'll update it as: [0-2][0-9]

Answer 3

Alternatively, you could use Array.filter here:

'5050.2011.DVD1943.XviD.AVI+117715.imported'
 .split(/[^\d]/ /* or /\D/ */)
 .filter(function(a){return +a>1899 && +a<=(new Date).getFullYear();});
 //=> ['2011','1943']

Or use match and filter :

'5050.2011.DVD1943.XviD.AVI+117715.imported'
 .match(/[^\D]+/g /* or /\d+/g */)
 .filter(function(a){return +a>1899 && +a<=(new Date).getFullYear();});
 //=> ['2011','1943']