stepDown method

void stepDown([
  1. int n
])

The HTMLInputElement.stepDown([n]) method decrements the value of a numeric type of input element by the value of the step attribute or up to n multiples of the step attribute if a number is passed as the parameter.

The method, when invoked, decrements 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.

Valid on all numeric, date, and time input types that support the step attribute, including date, month, week, time, , number, and range.

Given <input id="myTime" type="time" max="17:00" step="900" value="17:00">, invoking myTime.stepDown(3) will change the value to 16:15, decrementing the time by 3 * 900, or 45 minutes. myTime.stepDown(), with no parameter, would have resulted in 16:45, as n defaults to 1.

<!-- decrements by intervals of 900 seconds (15 minute) -->
<input type="time" max="17:00" step="900" />

<!-- decrements by intervals of 7 days (one week) -->
<input type="date" max="2019-12-25" step="7" />

<!-- decrements by intervals of 12 months (one year) -->
<input type="month" max="2019-12" step="12" />

However, calling stepDown on <input type="time" max="17:00" step="900"> would not set the value to 17:00, as one would expect — and as it does for stepUp when the input is <input type="time" min="17:00" step="900">. Instead, the first call to stepDown will set the initial value to 23:45 even though the max attribute is set. The second call will set the value to 17:00. And the third call to will set the value to 16:45.

let input1 = document.createElement("input");
input1.setAttribute("type", "time");
input1.setAttribute("min", "17:00");
input1.setAttribute("step", 900);
console.log(input1.value); // ""
input1.stepUp();
console.log(input1.value); // "17:00"
// However
let input2 = document.createElement("input");
input2.setAttribute("type", "time");
input2.setAttribute("max", "17:00");
input2.setAttribute("step", 900);
console.log(input2.value); // ""
input2.stepDown();
console.log(input2.value); // "23:45"
input2.stepDown();
console.log(input2.value); // "17:00"
input2.stepDown();
console.log(input2.value); // "16:45"

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 within the form control. The default value for the parameter, if not is passed, is 1. The method will not cause the value to go below the min value set or defy the constraints set by the step attribute. A negative value for n will increment the value, but will not increment beyond the max value.

If the value before invoking the stepDown() method is invalid, for example, if it doesn't match the constraints set by the step attribute, invoking the stepDown() 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 above), or if the step value is set to any, an InvalidStateError exception is thrown.

  • HTMLInputElement.stepDown

    • : Decrements the value by (step * n), where n defaults to 1 if not specified. Throws an InvalidStateError exception:

      • if the method is not applicable to for the current type value,
      • if the element has no step value,
      • if the value cannot be converted to a number,
      • if the resulting value is above the max or below the min.

Implementation

external void stepDown([int n]);