SliderViewModel

Property Overview

Property Details

declaredClass Stringreadonly inherited

The name of the class. The declared class name is formatted as esri.folder.className.

inputFormatFunction LabelFormatter

A function used to format user inputs. As opposed to labelFormatFunction, which formats thumb labels, the inputFormatFunction formats thumb values in the input element when the user begins to edit them.

The image below demonstrates how slider input values resemble corresponding slider values by default and won't match the formatting set in labelFormatFunction.

If you want to format slider input values so they match thumb labels, you can pass the same function set in labelFormatFunction to inputFormatFunction for consistent formatting.

However, if an inputFormatFunction is specified, you must also write a corresponding inputParseFunction to parse user inputs to understandable slider values. In most cases, if you specify an inputFormatFunction, you should set the labelFormatFunction to the same value for consistency between labels and inputs.

This property overrides the default input formatter, which formats by calling toString() on the input value.

See also:

• inputParseFunction

Example:

// Formats the slider input to abbreviated numbers with units
// e.g. a thumb at position 1500 will render with an input label of 1.5k
slider.inputFormatFunction = function(value, type){
  if(value >= 1000000){
    return (value / 1000000).toPrecision(3) + "m"
  }
  if(value >= 100000){
    return (value / 1000).toPrecision(3) + "k"
  }
  if(value >= 1000){
    return (value / 1000).toPrecision(2) + "k"
  }
  return value.toFixed(0);
}

inputParseFunction InputParser

Function used to parse slider inputs formatted by the inputFormatFunction. This property must be set if an inputFormatFunction is set. Otherwise the slider values will likely not update to their expected positions.

Overrides the default input parses, which is a parsed floating point number.

See also:

• inputFormatFunction

Example:

// Parses the slider input (a string value) to a number value understandable to the slider
// This assumes the slider was already configured with an inputFormatFunction
// For example, if the input is 1.5k this function will parse
// it to a value of 1500
slider.inputParseFunction = function(value, type, index){
  let charLength = value.length;
  let valuePrefix = parseFloat(value.substring(0,charLength-1));
  let finalChar = value.substring(charLength-1);

  if(parseFloat(finalChar) >= 0){
    return parseFloat(value);
  }
  if(finalChar === "k"){
    return valuePrefix * 1000;
  }
  if(finalChar === "m"){
    return valuePrefix * 1000000;
  }
  return value;
}

labelFormatFunction LabelFormatter

A function used to format labels. Overrides the default label formatter.

By default labels are formatted in the following way:

• When the data range is less than 10 ((max - min) < 10), labels are rounded based on the value set in the precision property.
• When the data range is larger than 10, labels display with a precision of no more than two decimal places, though actual slider thumb values will maintain the precision specified in precision.

Use this property to override the behavior defined above.

Example:

// For thumb values, rounds each label to whole numbers.
// Note the actual value of the thumb continues to be stored
// based on the indicated data `precision` despite this formatting
sliderViewModel.labelFormatFunction = function(value, type) {
  return (type === "value") ? value.toFixed(0) : value;
}

labels String[]readonly

An array of strings associated with values generated using an internal label formatter or the values returned from labelFormatFunction.

max Number

The maximum possible data/thumb value of the slider. In the constructor, if one of the values specified in values is greater than the max value specified in this property, then the max will update to the highest value in values.

Example:

sliderViewModel.max = 100;

min Number

The minimum possible data/thumb value of the slider. In the constructor, if one of the values specified in values is less than the min value specified in this property, then the min will update to the lowest value in values.

Example:

sliderViewModel.min = 0;

precision Number

Defines how slider values should be rounded. This number indicates the number of decimal places slider values should round to when they have been moved.

This value also indicates the precision of thumb labels when the data range (max - min) is less than 10.

When the data range is larger than 10, labels display with a precision of no more than two decimal places, though actual slider thumb values will maintain the precision specified in this property.

For example, given the default precision of 4, and the following slider configuration, The label of the thumb will display two decimal places, but the precision of the actual thumb value will not be lost even when the user slides or moves the thumb.

const slider = new SliderVM({
  min: 20,
  max: 100,  // data range of 80
  values: [50.4331],
  // thumb label will display 50.43
  // thumb value will maintain precision, so
  // value will remain at 50.4331
});

If the user manually enters a value that has a higher precision than what's indicated by this property, the precision of that thumb value will be maintained until the thumb is moved by the user. At that point, the value will be rounded according to the indicated precision.

If thumb labels aren't visible, they must be enabled with labelInputsEnabled.

Keep in mind this property rounds thumb values and shouldn't be used exclusively for formatting purposes. To format thumb labels, use the labelFormatFunction property.

Default Value:4

Example:

sliderViewModel.precision = 7;

state Stringreadonly

The state of the view model.

Possible Values:"ready"|"disabled"

thumbsConstrained Boolean

When false, the user can freely move any slider thumb to any position along the track. By default, a thumb's position is constrained to the positions of neighboring thumbs so you cannot move one thumb past another. Set this property to false to disable this constraining behavior.

Default Value:true

Example:

// allows the user to freely move slider
// thumbs to any position along the track
slider.viewModel.thumbsConstrained = false;

values Number[]

An array of numbers representing absolute thumb positions on the slider.

See also:

• setValue()

Example:

const slider = new SliderVM({
  min: 20,
  max: 100,  // data range of 80
  values: [50.4331],
  // thumb label will display 50.43
  // thumb value will maintain precision, so
  // value will remain at 50.4331
});

Method Overview

Method Details

defaultInputFormatFunction(value){String}

The default input format function available for use as a fallback in custom formatting implementations.

Parameter:

value Number The input value to format.

Returns:

Type	Description
String	The formatted input value.

defaultInputParseFunction(value){Number}

The default input parsing function available for use as a fallback in custom parsing implementations.

Parameter:

value String The thumb value to parse.

Returns:

Type	Description
Number	The parsed thumb value.

defaultLabelFormatFunction(value){String}

The default label format function, available for use as a fallback in custom formatting implementations.

Parameter:

value Number The thumb value to format.

Returns:

Type	Description
String	The formatted thumb value.

emit(type, event){Boolean}

Emits an event on the instance. This method should only be used when creating subclasses of this class.

Parameters:

type String The name of the event.

event Object optional The event payload.

Returns:

Type	Description
Boolean	true if a listener was notified

getBoundsForValueAtIndex(index){Object}

Returns the min and max bounds for a 'value' at the provided index. Also used internally to provide accessibility information via HTMLElement properties

Parameter:

index Number The index of the associated value.

Returns:

Type	Description
Object	Returns a simple object with bound information.

getLabelForValue(value, type, index){String}

Returns the formatted label for a provided value.

Parameters:

value Number The value from which to retrieve a formatted label.

type String optional The label type. Possible Values:"min"|"max"|"tick"|"values"

index Number optional The index of the label.

Returns:

Type	Description
String	Returns the formatted label.

hasEventListener(type){Boolean}

Indicates whether there is an event listener on the instance that matches the provided event name.

Parameter:

type String The name of the event.

Returns:

Type	Description
Boolean	Returns true if the class supports the input event.

on(type, listener){Object}

Registers an event handler on the instance. Call this method to hook an event with a listener.

Parameters:

type String|String[] A event type, or an array of event types, to listen for.

listener Function The function to call when the event is fired.

Returns:

Type	Description
Object	Returns an event handler with a remove() method that can be called to stop listening for the event(s). Property Type Description remove Function When called, removes the listener from the event.

Example:

view.on("click", function(event){
  // event is the event handle returned after the event fires.
  console.log(event.mapPoint);
});

setValue(index, value)

Updates a thumb value based on the provided index. The provided value must differ from the previous value. The provided value must also be between the min and max.

Parameters:

index Number The index of the thumb value in the associated values array.

value Number The new value to replace with the old value.

toPrecision(value){String}

Since: ArcGIS API for JavaScript 4.14

Rounds the given value to the number of decimal places specified in the precision property set on the view model.

Parameter:

value Number The thumb value to format.

Returns:

Type	Description
String	The input value rounded to the number of places specified in precision.

See also:

• precision

Event Overview

{oldValue: Number,type: "max",value: Number}

{oldValue: Number,type: "min",value: Number}

Event Details

max-change

Fires when a user changes the max value of the slider.

Properties:

oldValue Number The former max value (or bound) of the slider.

type String The type of the event. The value is always "max".

value Number The value of the max value (or bound) of the slider when the event is emitted.

min-change

Fires when a user changes the min value of the slider.

Properties:

oldValue Number The former min value (or bound) of the slider.

type String The type of the event. The value is always "min".

value Number The value of the min value (or bound) of the slider when the event is emitted.