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++){
	output += document.forms[0].check[i].value + ' ';
document.getElementById('span2').innerHTML = output;


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;

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- 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

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