How to validate html textbox not to allow leading and trailing whitespaces

Question

My html is:

 <input type="text" name="username">

If we write any validation also ,i need the function related stuff to happen in typescript but not java script.

You mean :<input required pattern=".*\S+.*" title="This field is required"> — soorapadman
– soorapadman, Commented Jun 1, 2017 at 11:24
Yeah i have to apply pattern.Correct.But what if I have to apply to say many text fields that too in different page .Is there a way to apply a pattern to all the text fields once at a time? — shinchan
– shinchan, Commented Jun 1, 2017 at 11:30
not possible with HTML but you can go with custom validator in typescript — soorapadman
– soorapadman, Commented Jun 1, 2017 at 11:32
Yes I wanted those validators written in typescript.Can you please give me a code example in typescript? — shinchan
– shinchan, Commented Jun 1, 2017 at 11:39

pablow · Accepted Answer · 2017-06-01 11:28:45Z

1

The simplest way is to use Regex in whatever implementation you need to filter for leading/trailing whitespace. If you want simple validation, try the HTML5 pattern attribute.

^(?=[A-Za-z0-9])([A-Za-z0-9\s]*)(?<=[A-Za-z0-9])$

https://regex101.com/r/bJCJBv/2

answered Jun 1, 2017 at 11:28

pablow

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