One of the main advantages of `<input type="tel">` is that it causes mobile browsers to display a special keyboard for entering phone numbers. For example, here's what the keypads look like on a couple of devices.
Examples of custom keyboards on mobile devices.
Firefox for Android
WebKit iOS (Safari/Chrome/Firefox)
単純な tel 入力欄
In its most basic form, a tel input can be implemented like this:
{{ EmbedLiveSample('A_simple_tel_input', 600, 40) }}
There is nothing magical going on here. When submitted to the server, the above input's data would be represented as, for example, `telNo=+12125553151`.
プレイスホルダー
Sometimes it's helpful to offer an in-context hint as to what form the input data should take. This can be especially important if the page design doesn't offer descriptive labels for each {{HTMLElement("input")}}. This is where placeholders come in. A placeholder is a value that demonstrates the form the `value` should take by presenting an example of a valid value, which is displayed inside the edit box when the element's `value` is `""`. Once data is entered into the box, the placeholder disappears; if the box is emptied, the placeholder reappears.
Here, we have an `tel` input with the placeholder `123-4567-8901`. Note how the placeholder disappears and reappears as you manipulate the contents of the edit field.
You can control not only the physical length of the input box, but also the minimum and maximum lengths allowed for the input text itself.
物理的な入力欄の寸法
The physical size of the input box can be controlled using the {{htmlattrxref("size", "input")}} attribute. With it, you can specify the number of characters the input box can display at a time. In this example, for instance, the `tel` edit box is 20 characters wide:
The `size` is separate from the length limitation on the entered telephone number. You can specify a minimum length, in characters, for the entered telephone number using the {{htmlattrxref("minlength", "input")}} attribute; similarly, use {{htmlattrxref("maxlength", "input")}} to set the maximum length of the entered telephone number.
The example below creates a 20-character wide telephone number entry box, requiring that the contents be no shorter than 9 characters and no longer than 14 characters.
Note: The above attributes do affect {{anch("Validation")}} — the above example's inputs will count as invalid if the length of the value is less than 9 characters, or more than 14. Most browser won't even let you enter a value over the max length.
Taking it a step farther, you can provide a list of default phone number values from which the user can select. To do this, use the {{htmlattrxref("list", "input")}} attribute. This doesn't limit the user to those options, but does allow them to select commonly-used telephone numbers more quickly. This also offers hints to {{htmlattrxref("autocomplete", "input")}}. The `list` attribute specifies the ID of a {{HTMLElement("datalist")}} element, which in turn contains one {{HTMLElement("option")}} element per suggested value; each `option`'s `value` is the corresponding suggested value for the telephone number entry box.
{{EmbedLiveSample("Offering_suggested_values", 600, 40)}}
With the {{HTMLElement("datalist")}} element and its {{HTMLElement("option")}}s in place, the browser will offer the specified values as potential values for the email address; this is typically presented as a popup or drop-down menu containing the suggestions. While the specific user experience may vary from one browser to another, typically clicking in the edit box presents a drop-down of the suggested email addresses. Then, as the user types, the list is adjusted to show only filtered matching values. Each typed character narrows down the list until the user makes a selection or types a custom value.
Here's a screenshot of what that might look like:
検証
As we've touched on before, it's quite difficult to provide a one-size-fits-all client-side validation solution for phone numbers. So what can we do? Let's consider some options.
重要: HTML のフォーム検証は、入力されたデータが正しい形式であることを保証するスクリプトの代用にはなりません。 HTML を調整して検証をくぐり抜けたり、完全に削除したりすることはとても簡単にできます。 HTML を完全にバイパスし、サーバーに直接データを送信することも可能です。サーバー側のコードが受信したデータの検証に失敗した場合、不適切な形式のデータ (または大きすぎるデータ、間違った種類のデータなど) が送信された場合に災害が発生するおそれがあります。
電話番号を必須にする
You can make it so that an empty input is invalid and won't be submitted to the server using the {{htmlattrxref("required", "input")}} attribute. For example, let's use this HTML:
The output looks like this:
{{EmbedLiveSample("Making_telephone_numbers_required", 700, 70)}}
パターンによる値検証
If you want to further restrict entered numbers so they also have to conform to a specific pattern, you can use the {{htmlattrxref("pattern","input")}} attribute, which takes as its value a {{Glossary("regular expression")}} that entered values have to match.
In this example we'll use the same CSS as before, but our HTML is changed to look like this:
<form>
<div>
<label for="telNo">Enter a telephone number (in the form xxx-xxx-xxxx): </label>
<input id="telNo" name="telNo" type="tel" required
pattern="[0-9]{3}-[0-9]{3}-[0-9]{4}">
<span class="validity"></span>
</div>
<div>
<button>Submit</button>
</div>
</form>
{{EmbedLiveSample("Pattern_validation", 700, 70)}}
Notice how the entered value is reported as invalid unless the pattern xxx-xxx-xxxx is matched; for instance, 41-323-421 won't be accepted. Neither will 800-MDN-ROCKS. However, 865-555-6502 will be accepted. This particular pattern is obviously only useful for certain locales — in a real application you'd probably have to vary the pattern used depending on the locale of the user.
例
In this example, we present a simple interface with a {{htmlelement("select")}} element that lets the user choose which country they're in, and a set of `<input type="tel">` elements to let them enter each part of their phone number; there is no reason why you can't have multiple `tel` inputs.
Each input has a {{htmlattrxref("placeholder","input")}} attribute to show a hint to sighted users about what to enter into it, a {{htmlattrxref("pattern","input")}} to enforce a specific number of characters for the desired section, and an `aria-label` attribute to contain a hint to be read out to screenreader users about what to enter into it.
The JavaScript is relatively simple — it contains an {{domxref("GlobalEventHandlers.onchange", "onchange")}} event handler that, when the `<select>` value is changed, updates the `<input>` element's `pattern`, `placeholder`, and `aria-label` to suit the format of telephone numbers in that country/territory.
The example looks like this:
{{EmbedLiveSample('Examples', 600, 140)}}
This is an interesting idea, which goes to show a potential solution to the problem of dealing with international phone numbers. You would have to extend the example of course to provide the correct pattern for potentially every country, which would be a lot of work, and there would still be no foolproof guarantee that the users would enter their numbers correctly.
It makes you wonder if it is worth going to all this trouble on the client-side, when you could just let the user enter their number in whatever format they wanted on the client-side and then validate and sanitize it on the server. But this choice is yours to make.