i am new at programming and my I think my question is easy, but I don't have any ideas. How to check if the number of characters in a text field matches 11? I tried this but I don't think that's a good lead.
<form name="formz">
<input type='text' name='numbere' id="p" maxlength="11">
</form>
<button onclick="writee()">x</button>
<script>
function writee(){
win=window.open(" ","tab","width=300,height=350")
win.document.open()
var l = document.forms["formz"].numbere;
if(l.length==11){
win.document.write( "under 11 characters <br/>");
}else{
win.document.write( " 11 characters <br/>");
}
}
Add minLength="11"
to the same input.
Note that if you need more secure validation, you will also have to check the values on the server side. The Html attributes will only work for client-side validation. This means that someone who is determined to circumvent the length requirements could edit the source code in their browser and bypass your restrictions. For more casual use cases that are not security sensitive, the HTML attributes should suffice.
In terms of HTML please have a look at the input's attributes: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input
In JavaScript it has been answered here: Form Validation Vanilla JS
To further your knowledge about Regex validation, here are some examples: https://regex101.com/library?orderBy=RELEVANCE&page=1&search=validation