Method Overview

Method Details

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:

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

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

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:

/// <amd-dependency path="esri/core/tsSupport/declareExtendsHelper" name="__extends" />
/// <amd-dependency path="esri/core/tsSupport/decorateHelper" name="__decorate" />

import Accessor = require("esri/core/Accessor");
import { subclass, property, declared, cast } from "esri/core/tsSupport/declare";

@subclass()
class Color extends declared(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(classFunction){Function}

This parameter decorator is used to define the function or class for a parameter of a method.

Parameter:

classFunction Function The function or class to cast the parameter

Returns:

Type	Description
Function	The method descriptor.

See also:

• Accessor

Example:

/// <amd-dependency path="esri/core/tsSupport/declareExtendsHelper" name="__extends" />
/// <amd-dependency path="esri/core/tsSupport/decorateHelper" name="__decorate" />

import Accessor = require("esri/core/Accessor");
import { subclass, property, declared } from "esri/core/tsSupport/declare";

@subclass()
class QueryTask extends declared(Accessor) {

  execute(@cast(Query) query: Query): IPromise<FeatureSet> {
    return ...;
  }

}

declared(baseClass, mixinClasses){*}

Since: ArcGIS API for JavaScript 4.2

A function that can be used as a class. It extends expression and is used in conjunction with the @subclass decorator to create a class compatible to dojo.declare. Please refer to the subclass documentation for further information.

Parameters:

baseClass The class to extend.

mixinClasses Object repeatable The mixin classes used to extend the base class.

Returns:

Type	Description
*	The first baseClass.

Example:

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

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. Many times this decorator is used in conjunction with the @renderable decorator.

Parameters:

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 Indicates whether the property is read-only, default is false. 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(declaredClass){Function}

A class decorator that must be used together with the declared function to create a class compatible to dojo.declare. It supports both single and multiple inheritance and can be considered the underlying functionality needed when creating 4.x classes.

Parameter:

declaredClass String optional The subclass name.

Returns:

Type	Description
Function	The class decorator.

Examples:

// Single inheritance - typescript syntax which creates a subclass that extends the Accessor class.
@subclass("my.custom.class")
class MyCustomClass extends declared(Accessor) {
  // ...
}

// Multiple inheritance - typescript syntax which creates a subclass that extends multiple classes
// Use declaration merging to add mixins to the SceneLayer type
interface SceneLayer extends SceneService {
}

// provide a fully qualified namespace for the resulting subclass
@subclass("esri.layers.SceneLayer")
class SceneLayer extends declared(Layer, SceneService) {
  // do something
}