Javascript functions for form fields

4.14 (21 votes)

A number of useful functions for accessing various properties and values of form fields.

Getting the selected index and value from a select list

function getValues(){
var dd = document.getElementById('dropdown');
theindex = dd.options[dd.selectedIndex].value;
thevalue = dd.options[dd.selectedIndex].text;
var span = document.getElementById('span1');
span.innerHTML = '  Selected Index: ' + theindex + 
	', Selected Value: ' + thevalue
}

Detect which checkbox was ticked or unticked, and an array of selected values

function getchk(val){
var output = 'You clicked ' + val + ' Selected: ';
for(var i = 0; i < document.forms[0].check.length; i++){
	if(document.forms[0].check[i].checked)
	output += document.forms[0].check[i].value + ' ';
	}
document.getElementById('span2').innerHTML = output;
}

1
2
3
4

Get the text and number of characters from a text box

function getText(){
var txt = document.getElementById('txt');
var output = txt.value;
var length = output.length;
document.getElementById('span3').innerHTML = 'Count: ' + length
	+ ' Text: ' + output;
}

You might also like...

Date Posted:
Last Updated:
Posted by:
Total Views to date: 11145

3 Comments

- Deep

I have a form which ask for YEAR. How can I restrict user to only allow to input numbers.

I have put a validation which doesn't allow non-numeric but it is tested after the form is POSTed.

Any suggestion for suppressing the non-numeric keys in "NUMERIC-ONLY" text box ???

- Mike

You should use a Javascript library like jQuery's Validate plug in to manage that kind of thing in the browser. In fact, this whole article is pretty obsolete because jQuery makes the tasks outlined above much easier.

- tiara

verry good

Recent Comments

Sivu 19/10/2016 08:21
In response to Entity Framework Core TrackGraph For Disconnected Data
Oh that's very very very nice ! Thanks for the write up Mike, much appreciated for the taking the to...

Mark 12/10/2016 16:42
In response to ASP.NET Web Pages vNext or Razor Pages
Although "Web Pages" was removed from the roadmap, has it just been renamed to "Razor Pages"?...

Satyabrata 12/10/2016 09:20
In response to Entity Framework Core TrackGraph For Disconnected Data
Nice article. Please write more articles featuring ASP.Net web pages. Thank you...

Julian 26/09/2016 14:27
In response to Loading ASP.NET Core MVC Views From A Database Or Other Location
Fantastic, many thanks Mike! Had got half way down this road before finding your article - saved...

Abolfazl Roshanzamir 14/09/2016 05:36
In response to Loading ASP.NET Core MVC Views From A Database Or Other Location
Nice article. Thanke you so much ....

cyrus 02/09/2016 15:12
In response to ASP.NET Web Pages vNext or Razor Pages
I've got some news. As Damian stated in this link: https://github.com/aspnet/Mvc/issues/5208 “We...

Simon 01/09/2016 08:00
In response to Loading ASP.NET Core MVC Views From A Database Or Other Location
Thanks Mike, nice post and exactly what I was looking for. Like you said, I think I'll opt to the...

dave 20/08/2016 14:57
In response to ASP.NET Web Pages vNext or Razor Pages
Do SimplemembershipProvider in viewpages is supported?...

Steven 18/08/2016 04:40
In response to Entity Framework Code First and Stored Procedures
Can you provide the directives (using statements) you're using for EF7 example?...

yousaid 17/08/2016 22:08
In response to ASP.NET Web Pages vNext or Razor Pages
Increasingly, learning a Microsoft tool is no longer worth the return on investment. Too many tools...