HTMLInputElement: stepUp() method

The HTMLInputElement.stepUp() method increments the value of a numeric type of <input> element by the value of the step attribute, or the default step value if the step attribute is not explicitly set. The method, when invoked, increments the value by (step * n), where n defaults to 1 if not specified, and step defaults to the default value for step if not specified.

Input type	Default step value	Example step declaration
date	1 (day)	7 day (one week) increments: <input type="date" min="2019-12-25" step="7">
month	1 (month)	12 month (one year) increments: <input type="month" min="2019-12" step="12">
week	1 (week)	Two week increments: <input type="week" min="2019-W23" step="2">
time	60 (seconds)	900 second (15 minute) increments: <input type="time" min="09:00" step="900">
datetime-local	1 (day)	Same day of the week: <input type="datetime-local" min="019-12-25T19:30" step="7">
number	1	0.1 increments <input type="number" min="0" step="0.1" max="10">
range	1	Increments by 2: <input type="range" min="0" step="2" max="10">

The method, when invoked, changes the form control's value by the value given in the step attribute, multiplied by the parameter, within the constraints set on the form control. The default value for the parameter, if no value is passed, is 1. The method will not cause the value to exceed the set max value, or defy the constraints set by the step attribute.

If the value before invoking the stepUp() method is invalid—for example, if it doesn't match the constraints set by the step attribute—invoking the stepUp() method will return a value that does match the form controls constraints.

If the form control is non time, date, or numeric in nature, and therefore does not support the step attribute (see the list of supported input types in the table above), or if the step value is set to any, an InvalidStateError exception is thrown.

stepUp()
stepUp(stepIncrement)

<p>
  <label for="theNumber">
    Enter a number between 0 and 400 that is divisible by 5:
  </label>
  <input type="number" step="5" id="theNumber" min="0" max="400" />
</p>
<p>
  <label>
    Enter how many values of step you would like to increment by or leave it
    blank:
  </label>
  <input type="number" step="1" id="incrementInput" min="0" max="25" />
</p>
<input type="button" value="Increment" id="theButton" />

/* make the button call the function */
const button = document.getElementById("theButton");
button.addEventListener("click", () => {
  stepOnUp();
});

function stepOnUp() {
  let input = document.getElementById("theNumber");
  let val = document.getElementById("incrementInput").value;

  if (val) {
    /* increment with a parameter */
    input.stepUp(val);
  } else {
    /* or without a parameter. Try it with 0 */
    input.stepUp();
  }
}

input:invalid {
  border: red solid 3px;
}