HTML <input> id Attribute

The id attribute on an <input> tag assigns an identifier to the input control. The identifier must be unique across the page.

Example

#

A unique id attribute on each of the 4 <input> elements.

Contact Details





<form action="/tutorial/action.html">
  <fieldset>
    <legend>Contact Details</legend>

    <input type="text" placeholder="First name" id="firstname" name="firstname"><br /><br />
    <input type="text" placeholder="Last name" id="lastname" name="lastname"><br /><br />
    <input type="text" placeholder="Email" id="email" name="email"><br /><br />

    <input type="submit" id="submit" value="Submit">
  </fieldset>
</form>

Using id

The id attribute assigns an identifier to the <input> element.

The identifier must be unique across the page.

The id allows programmatic access to the <input> element.

Tip:  id is a global attribute that can be applied to any HTML element.


Syntax

<input id="identifier" />

Values

#

Value Description
identifier A unique alphanumeric string. The id value must begin with a letter ([aside-Zaside-z]) and may be followed by any number of letters, digits ([0-9]), hyphens (-), underscores (_), colons (:), and periods (.).

More Examples

An <input> element with a unique id.
Clicking the button will display the <value> of the input field.




<label>Title</label><br />
<input id="myinput" type="text" value="Computer Literacy">
  
<br/><br/>
<button onclick="show();">Show input value</button>

<script>
  let show = () => {
    let input = document.getElementById("myinput");
    alert("Value = " + input.value);
  }
</script>

Code explanation

The id attribute assigns a unique identifier for the <input> element.

Clicking the button calls JavaScript which locates the <input> using the id.

Finally, the value of the <input> element is displayed in an alert box.


Browser support

Here is when id support started for each browser:

Chrome
1.0 Sep 2008
Firefox
1.0 Sep 2002
IE/Edge
1.0 Aug 1995
Opera
1.0 Jan 2006
Safari
1.0 Jan 2003

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