<input> элементы типаnumber используются для того, чтобы дать возможность пользователю ввести число. У них есть встроенная валидация, запрещающая вводить нечисловые значения. Браузер может предоставить возможность увеличить или уменьшить значение специальными стрелками, используя мышь или просто двигая пальцем по экрану.

Интерактивный пример

<label for="tentacles">Number of tentacles (10-100):</label><input type="number" name="tentacles" min="10" max="100" />

label {  display: block;  font:    1rem "Fira Sans",    sans-serif;}input,label {  margin: 0.4rem 0;}

В браузерах, которые не поддерживают типnumber, типnumber приводится кtext.

Value

Number, представляющий значение введённого числа. Вы можете установить значение по умолчанию, вставив значение в атрибутvalue, например:

<input type="number" value="42" />

Additional attributes

In addition to the attributes commonly supported by all<input> types, inputs of typenumber support these attributes:

max

The maximum value to accept for this input. If thevalue entered into the element exceeds this, the element failsconstraint validation. If the value of themax attribute isn't a number, then the element has no maximum value.

This value must be greater than or equal to the value of themin attribute.

min

Минимальное значение, которое может принять это поле ввода. Если значение атрибутаvalue меньше, то элемент не проходитпроверку ограничений. Если указанное дляmin значение не является числом, то у поля ввода нет минимального значения.

Это значение должно быть меньше или равно значению атрибутаmax.

step

Атрибутstep – это число, которое определяет точность, с которой задаётся значение, или специальное значениеany, описанное ниже. Только значения, кратные шагу (min, если задано, иначеvalue, или подходящее стандартное значение, если ни одно из двух не задано) будут корректными.

Строковое значениеany означает, что никакое значение шага не задано и допустимо любое значение (в пределах других ограничений, таких какmin иmax).

Стандартное значение шага для поля вводаnumber – это1, что позволяет вводить только целые числа,если только не задать значение шага нецелым числом.

Using number inputs

<input type="number"> elements can help simplify your work when building the user interface and logic for entering numbers into a form. When you create a number input with the propertype value,number, you get automatic validation that the entered text is a number, and usually a set of up and down buttons to step the value up and down.

Mobile browsers further help with the user experience by showing a special keyboard more suited for entering numbers when the user tries to enter a value. The following screenshot is taken from Firefox for Android:

A simple number input

In its most basic form, a number input can be implemented like this:

<label for="ticketNum">Number of tickets you would like to buy:</label><input type="number" name="ticketNum" value="0" />

A number input is considered valid when empty and when a single number is entered, but is otherwise invalid. If therequired attribute is used, the input is no longer considered valid when empty.

Placeholders

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<input>. This is whereplaceholders come in. A placeholder is a value most commonly used to provide a hint as to the format the input should takevalue. It is displayed inside the edit box when the element'svalue is"". Once data is entered into the box, the placeholder disappears; if the box is emptied, the placeholder reappears.

Here, we have annumber input with the placeholder"Multiple of 10". Note how the placeholder disappears and reappears as you manipulate the contents of the edit field.

<input type="number" placeholder="Multiple of 10" />

Controlling step size

By default, the up and down buttons provided for you to step the number up and down will step the value up and down by 1. You can change this by providing astep attribute, which takes as its value a number specifying the step amount. Our above example contains a placeholder saying that the value should be a multiple of 10, so it makes sense to add astep value of 10:

<input type="number" placeholder="multiple of 10" step="10" />

In this example you should find that the up and down step arrows will increase and decrease the value by 10 each time, not 1. You can still manually enter a number that's not a multiple of 10, but it will be considered invalid.

Specifying minimum and maximum values

You can use themin andmax attributes to specify a minimum and maximum value that the field can have. For example, let's give our example a minimum of 0, and a maximum of 100:

<input type="number" placeholder="multiple of 10" step="10" min="0" max="100" />

In this updated version, you should find that the up and down step buttons will not allow you to go below 0 or above 100. You can still manually enter a number outside these bounds, but it will be considered invalid.

Allowing decimal values

One issue with number inputs is that their step size is 1 by default — if you try to enter a number with a decimal, such as "1.0", it will be considered invalid. If you want to enter a value that requires decimals, you'll need to reflect this in thestep value (e.g.step="0.01" to allow decimals to two decimal places). Here's a simple example:

<input type="number" placeholder="1.0" step="0.01" min="0" max="10" />

See that this example allows any value between 0.0 and 10.0, with decimals to two places. "9.52" is valid, but "9.521" is not, for example.

Controlling input size

<input> elements of typenumber don't support form sizing attributes such assize. You'll have to resort toCSS to change the size of these controls.

For example, to adjust the width of the input to be only as wide as is needed to enter a three-digit number, we can change our HTML to include an ID and to shorten our placeholder since the field will be too narrow for the text we have been using so far:

<input  type="number"  placeholder="x10"  step="10"  min="0"  max="100"  />

Then we add some CSS to narrow the width of the element with the IDnumber:

#number {  width: 3em;}

The result looks like this:

Offering suggested values

You can provide a list of default options from which the user can select by specifying thelist attribute, which contains as its value the ID of a<datalist>, which in turn contains one<option> element per suggested value; eachoption'svalue is the corresponding suggested value for the number entry box.

<input type="number" name="ticketNum" list="defaultNumbers" /><span></span><datalist>  <option value="10045678"></option>  <option value="103421"></option>  <option value="11111111"></option>  <option value="12345678"></option>  <option value="12999922"></option></datalist>

Validation

We have already mentioned a number of validation features ofnumber inputs, but let's review them now:

• <input type="number"> elements automatically invalidate any entry that isn't a number (or empty, unlessrequired is specified).
• You can use therequired attribute to make an empty entry invalid, i.e. the input has to be filled in.
• You can use thestep attribute to constrain valid values to a certain set of steps (e.g. multiples of 10).
• You can use themin andmax attributes to constrain valid values to lower and upper bounds.

The following example exhibits all of the above features, as well as using some CSS to display valid and invalid icons when the input value is valid/invalid:

<form>  <div>    <label for="balloons">Number of balloons to order (multiples of 10):</label>    <input           type="number"      name="balloons"      step="10"      min="0"      max="100"      required />    <span></span>  </div>  <div>    <input type="submit" />  </div></form>

Try submitting the form with different invalid values entered — e.g. no value, a value below 0 or above 100, a value that is not a multiple of 10, or a non-numerical value — and see how the error messages the browser gives you differ with different ones.

The CSS applied to this example is as follows:

div {  margin-bottom: 10px;}input:invalid + span:after {  content: "✖";  padding-left: 5px;}input:valid + span:after {  content: "✓";  padding-left: 5px;}

Here we use the:invalid and:valid pseudo classes to display an appropriate invalid or valid icon as generated content on the adjacent<span> element, indicating if the current value is valid. We put it on a separate<span> element for added flexibility; some browsers don't display generated content very effectively on some types of form inputs (read for example the section on<input type="date"> validation).

Pattern validation

<input type="number"> elements do not support use of thepattern attribute for making entered values conform to a specific regex pattern. The rationale for this is that number inputs won't be valid if they contain anything except numbers, and you can constrain the minimum and maximum number of valid digits using themin andmax attributes, as explained above.

Examples

We've already covered the fact that by default, the increment is 1, and you can use thestep attribute to allow decimal inputs. Let's take a closer look. In the following example we've set up a form for entering the user's height; it defaults to accepting a height in meters, but you can click the relevant button to change the form to accept feet and inches instead. The input for the height in meters accepts decimals to two places.

The HTML looks like this:

<form>    <div>        <label for="meters">Enter your height — meters:</label>        <input type="number" name="meters" step="0.01" min="0" placeholder="e.g. 1.78" required>        <span></span>    </div>        <span>Enter your height — </span>        <label for="feet">feet:</label>        <input type="number" name="feet" min="0" step="1">        <span></span>        <label for="inches">inches:</label>        <input type="number" name="inches" min="0" max="11" step="1">        <span></span>    </div>    <div>      <input type="button" value="Enter height in feet and inches">    </div>    <div>        <input type="submit" value="Submit form">    </div></form>

You'll see that we are using many of the attributes we've already looked at in the article earlier on. Since we want to accept a meter value in centimeters, we've set thestep value to0.01, so that values like 1.78 are not seen as invalid. We've also provided a placeholder for that input.

We've hidden the feet and inches inputs initially usingclass="hidden" so that meters is the default entry type.

Now on to the CSS — this looks very similar to the validation styling we saw before; nothing remarkable here:

div {  margin-bottom: 10px;  position: relative;}input[type="number"] {  width: 100px;}input + span {  padding-right: 30px;}input:invalid + span:after {  position: absolute;  content: "✖";  padding-left: 5px;}input:valid + span:after {  position: absolute;  content: "✓";  padding-left: 5px;}

And finally, the #".metersInputGroup");var feetInputGroup = document.querySelector(".feetInputGroup");var metersInput = document.querySelector("#meters");var feetInput = document.querySelector("#feet");var inchesInput = document.querySelector("#inches");var switchBtn = document.querySelector('input[type="button"]');switchBtn.addEventListener("click", function () { if (switchBtn.getAttribute("class") === "meters") { switchBtn.setAttribute("class", "feet"); switchBtn.value = "Enter height in meters"; metersInputGroup.style.display = "none"; feetInputGroup.style.display = "block"; feetInput.setAttribute("required", ""); inchesInput.setAttribute("required", ""); metersInput.removeAttribute("required"); metersInput.value = ""; } else { switchBtn.setAttribute("class", "meters"); switchBtn.value = "Enter height in feet and inches"; metersInputGroup.style.display = "block"; feetInputGroup.style.display = "none"; feetInput.removeAttribute("required"); inchesInput.removeAttribute("required"); metersInput.setAttribute("required", ""); feetInput.value = ""; inchesInput.value = ""; }});