Obligatory beginning of the input digits 5739, how to do?

Hello and good evening.

There is input field, you need to start mandatory this field was with the digits 5739, another to enter that it was impossible.
How to implement this?
March 19th 20 at 09:05
4 answers
March 19th 20 at 09:07
Solution
do any span with text 5739 "inside" the input, at the input, respectively the indentation under the text
and the user to type less, and no need to check ...
March 19th 20 at 09:09
Solution
Mask ' field in Advance to substitute the numbers in the input and not allow to remove
March 19th 20 at 09:11
March 19th 20 at 09:13
https://codepen.io/anon/pen/drxWXp

but it is better to type less, and then add somewhere 5739 + input.value

Find more questions by tags HTMLJavaScript