decorators | API Reference | ArcGIS Maps SDK for JavaScript 4.31

See also

Method Overview

Return Type	Summary	Object
Function	A property decorator that creates a two-way binding between the property it decorates and an inner property of one of its members.	decorators
Function	This method decorator is used to define the method that will cast a property from a class.	decorators
Function	This property decorator is used to define the function or class for a property.	decorators
Function	This convenience decorator is used to define an Accessor property.	decorators
Function	This decorator is used to define an Accessor subclass.	decorators

Method Details

aliasOf Method aliasOf(propertyName){Function}

A property decorator that creates a two-way binding between the property it decorates and an inner property of one of its members.

Parameter

propertyName String

The aliased property name.

Returns

Type	Description
Function	The property decorator.

Examples

// property example
@aliasOf("viewModel.name")
name: string = "name";

// method example
@aliasOf("viewModel.someMethod")
someMethod: () => string;

cast Method cast(propertyName){Function}

This method decorator is used to define the method that will cast a property from a class.

Parameter

propertyName String

The property name the function will cast.

Returns

Type	Description
Function	The method descriptor.

See also

Accessor

Example

import Accessor from "esri/core/Accessor";
import { subclass, property, cast } from "esri/core/accessorSupport/decorators";

@subclass()
class Color extends Accessor {

  @property()
  r: number = 0;

  @property()
  g: number = 0;

  @property()
  b: number = 0;

  @property()
  a: number = 1;

  @cast("r")
  @cast("g")
  @cast("b")
  protected castComponent(value) {
    // cast method that clamp the value that
    // will be set on r, g or b between 0 and 255
    return Math.max(0, Math.min(255, value));
  }

  @cast("a")
  protected castAlpha(value) {
    // cast method that clamp the value that
    // will be set on a between 0 and 255
    return Math.max(0, Math.min(1, value));
  }
}

cast Method cast(functionOrClass){Function}

This property decorator is used to define the function or class for a property.

Parameter

functionOrClass Function

The function or class to cast the property

Returns

Type	Description
Function	The property descriptor.

See also

Accessor

Example

import Accessor from "esri/core/Accessor";
import { subclass, property, cast } from "esri/core/accessorSupport/decorators";

function clampRGB(component: number) {
  return Math.min(Math.max(component, 0), 255);
}

function clampAlpha(alpha: number) {
  return Math.min(Math.max(alpha, 0), 1);
}

@subclass()
class Color extends Accessor {

  @property()
  @cast(clampRGB)
  r: number = 0;

  @property()
  @cast(clampRGB)
  g: number = 0;

  @property()
  @cast(clampRGB)
  b: number = 0;

  @property()
  @cast(clampRGB)
  a: number = 1;
}

property Method property(propertyMetadata){Function}

This convenience decorator is used to define an Accessor property. Any property defined with this decorator can now be get and set. In addition, you can watch for any property changes.

Parameters

Specification

propertyMetadata Object

optional

An object describing the property.

Specification

dependsOn String []

optional

Property names of dependencies.

type Function

optional

The constructor used to autocast the property.

cast Function

optional

The function to use to autocast the property. Alternative to define the type. The function is called with the value set by the user and should return the cast value.

readOnly Boolean

optional

Default Value: false

Indicates whether the property is read-only.

constructOnly Boolean

optional

Default Value: false

Indicates whether the property can be set during construction but is otherwise read-only.

aliasOf String

optional

The property decorator that creates a two-way binding between the property it decorates and an inner property of one of its members.

value Object

optional

The default value for the property.

Returns

Type	Description
Function	The property descriptor.

See also

Accessor

Example

// typescript syntax to specify the property.
@property()
title: string = "Awesome Title!"

subclass Method subclass(declaredClass){Function}

This decorator is used to define an Accessor subclass. Any subclass of Accessor must use the @subclass decorator.

Parameter

declaredClass String

optional

The subclass name.

Returns

Type	Description
Function	The class decorator.

Example

// TypeScript syntax which creates a subclass that extends the Accessor class.
@subclass("my.custom.class")
class MyCustomClass extends Accessor {
  // ...
}