Custom HTML5 validation pattern: YYYY.anynumber - regex

Question

I googled a lot, but I'm stuck.
There is a cool thing in HTML5, required patterns. It's great for emails / phones / dates validation. I use it in my small project for checking numbers. What I need is a pattern for:
YYYY.ordernumber
Order number may be any number from 1 to 1000000.
I tried to modify some YYYY.MM patterns for my case, but with no luck. What ever I type in does not pass the validation.
Can anyone please help?

Answer 1

UPDATE: Added a lookahead to ensure 'ordernumber' is > 0 (thanks to M42's remark in comments).
You can use those two attributes with your <input>:
pattern="^[0-9]{4}\.(?!0+$)([0-9]{1,6}|1000000)$"
required
E.g.
<input type="text" placeHolder="YYYY.ordernumber" title="YYYY.ordernumber"
pattern="^[0-9]{4}\.(?!0+$)([0-9]{1,6}|1000000)$" required />
See, also, this short demo.
Short explanation of the regex:
^[0-9]{4}\.(?!0+$)([0-9]{1,6}|1000000)$ _____________
^\______/\/\_____/ \________/\______/ ^___|match the end|
| | | |_(*2) |_ |_____ |of the string|
_______| | |____ | |
_________|__ _______|_____ _|______ _|________ _|______
|match the | |match exactly| |match a | |match 1 to| |or match|
|beggining of| |4 digits | |dot (*1)| |6 digits | |1000000 |
|the string |
(*1): '.' is a special character in regex, so it has to be escaped ('.').
(*2): This is a negative lookahead which does consume any characters, but looks ahead and makes sure that the rest of the string in not consisted of zeros only.
Just for the sake of completeness:
I must point out the fact that [0-9] matches only digits 0-9. If you need to also match other digit characters, such as for example Eastern Arabic numerals (٠١٢٣٤٥٦٧٨٩), you can use \d instead.