HTML input - name vs. id

Question

When using the HTML <input> tag, what is the difference between the use of the name and id attributes especially that I found that they are sometimes named the same?

Answer 1

the name attribute is used for posting to e.g. a webserver. The id is primarily used for css (and javascript). Suppose you have this setup:

<input id="message_id" name="message_name" type="text" />

in order to get the value with PHP when posting your form, it will use the name-attribute, like this:

$_POST["message_name"];

The id is used for styling, as said before, for when you want to use specific css.

#message_id
{
    background-color: #cccccc;
}

Of course, you can use the same denomination for your id and name-attribute. These two will not interfere with each other.

also, name can be used for more items, like when you are using radiobuttons. Name is then used to group your radiobuttons, so you can only select one of those options.

<input id="button_1" type="radio" name="option" />
<input id="button_2" type="radio" name="option" />

And in this very specific case, I can further say how id is used, because you will probably want a label with your radiobutton. Label has a for-attribute, which uses the id of your input to link this label to your input (when you click the label, the button is checked). Example can be found below

<input id="button_1" type="radio" name="option" /><label for="button_1">Text for button 1</label>
<input id="button_2" type="radio" name="option" /><label for="button_2">Text for button 2</label>

And I guess that's about it.

Answer 2

The name attribute on an input is used by its parent HTML <form>s to include that element as a member of the HTTP form in a POST request or the query string in a GET request.

The id should be unique as it should be used by JavaScript to select the element in the DOM for manipulation and used in CSS selectors.

Answer 3

The name definies what the name of the attribute will be as soon as the form is submitted. So if you want to read this attribute later you will find it under the "name" in the POST or GET Request.

Whereas the id is used to adress a field or element in javascript or css.

Answer 4

If you are using JavaScript/CSS, you must use 'id' of control to apply any CSS/JavaScript stuff on it.

If you use name, CSS won't work for that control. As an example, if you use a JavaScript calendar attached to a textbox, you must use id of text control to assign it the JavaScript calendar.

Answer 5

IDs must be unique

...within page DOM element tree so each control is individually accessible by its id on the client side (within browser page) by

• Javascript scripts loaded in the page
• CSS styles defined on the page

Having non-unique IDs on your page will still render your page, but it certainly won't be valid. Browsers are quite forgiving when parsing invalid HTML. but don't do that just because it seems that it works.

Names are quite often unique but can be shared

...within page DOM between several controls of the same type (think of radio buttons) so when data gets POSTed to server only a particular value gets sent. So when you have several radio buttons on your page, only the selected one's value gets posted back to server even though there are several related radio button controls with the same name.

Addendum to sending data to server: When data gets sent to server (usually by means of HTTP POST request) all data gets sent as name-value pairs where name is the name of the input HTML control and value is its value as entered/selected by the user. This is always true for non-Ajax requests. In Ajax requests name-value pairs can be independent of HTML input controls on the page, because developers can send whatever they want to the server. Quite often values are also read from input controls, but I'm just trying to say that this is not necessarily the case.

When names can be duplicated

It may sometimes be beneficial that names are shared between controls of any form input type. But when? You didn't state what your server platform may be, but if you used something like Asp.net MVC you get the benefit of automatic data validation (client and server) and also binding sent data to strong types. That means that those names have to match type property names.

Now suppose you have this scenario:

• you have a view with a list of items of the same type
• user usually works with one item at a time, so they will only enter data with one item alone and send it to server

So your view's model (since it displays a list) is of type IEnumerable<SomeType> but your server side only accepts one single item of type SomeType.

How about name sharing then?

Each item is wrapped within its own FORM element and input elements within it have the same names so when data gets to the server (from any element) it gets correctly bound to the string type expected by the controller action.

This particular scenario can be seen on my Creative stories mini-site. You won't understand the language, but you can check out those multiple forms and shared names. Never mind that IDs are also duplicated (which is a rule violation) but that could be solved. It just doesn't matter in this case.

Answer 6

name is used for form submission in DOM (Document Object Model).

ID is used to unique name of html controls in DOM specially for Javascript & CSS