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In an HTML document I have a form and from the form there are several input elements (not a fix number). I want to get the last input element.

I tried:

imputs=document.getElementsByTagName('input');
lastIndex=imputs.length;
imputs[lastIndex] - here I get undefined

I don't understand why the following code works and the previous not:

lastIndex=10;
imputs[lastIndex]

In an HTML document I have a form and from the form there are several input elements (not a fix number). I want to get the last input element.

I tried:

imputs=document.getElementsByTagName('input');
lastIndex=imputs.length;
imputs[lastIndex] - here I get undefined

I don't understand why the following code works and the previous not:

lastIndex=10;
imputs[lastIndex]

• javascript
• dom

Share Improve this question Follow edited Feb 21, 2013 at 21:34 MikeM 27.4k44 gold badges6767 silver badges8080 bronze badges asked Feb 21, 2013 at 21:31 telebogtelebog 1,90655 gold badges2626 silver badges3737 bronze badges

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3 Answers 3

Sorted by: Reset to default 5

imputs = document.getElementsByTagName('input');
lastIndex = imputs.length;
imputs[lastIndex - 1] 

Arrays ([upd.] and NodeList, etc.) are 0 based in JavaScript.

Also: i*n*puts. ;)

---

An alternative method would be document.querySelector('...') with ":last-of-type":

document.querySelector('input:last-of-type').value = '42';

http://jsfiddle/zUVg5/

The getElementsByTagName() function returns a NodeList containing all of the elements that have the specified tag name. These elements can be accessed using the square bracket notation by specifying an index.

However, elements in the list are indexed from 0 to N, where N is one less than the length of the list. In order to get the last element, you actually want imputs[imputs.length - 1];.

Arrays are zero based. Length will give you an item which is undefined because it is after the end of the array. You should use

imputs[lastIndex - 1]

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