reflect-metadata

Applies a set of decorators to a target object.

Parameter decorators

An array of decorators.

Parameter target

The target object.

Returns

The result of applying the provided decorators.

Remarks

Decorators are applied in reverse order of their positions in the array.

Example 1

class Example { }

// constructor Example = Reflect.decorate(decoratorsArray, Example);

Applies a set of decorators to a property of a target object.

Parameter decorators

An array of decorators.

Parameter target

The target object.

Parameter propertyKey

The property key to decorate.

Parameter attributes

A property descriptor.

Remarks

Decorators are applied in reverse order.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod() { } method() { } }

// property (on constructor) Reflect.decorate(decoratorsArray, Example, "staticProperty");

// property (on prototype) Reflect.decorate(decoratorsArray, Example.prototype, "property");

// method (on constructor) Object.defineProperty(Example, "staticMethod", Reflect.decorate(decoratorsArray, Example, "staticMethod", Object.getOwnPropertyDescriptor(Example, "staticMethod")));

// method (on prototype) Object.defineProperty(Example.prototype, "method", Reflect.decorate(decoratorsArray, Example.prototype, "method", Object.getOwnPropertyDescriptor(Example.prototype, "method")));

Define a unique metadata entry on the target.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter metadataValue

A value that contains attached metadata.

Parameter target

The target object on which to define metadata.

Example 1

class Example { }

// constructor Reflect.defineMetadata("custom:annotation", options, Example);

// decorator factory as metadata-producing annotation. function MyAnnotation(options): ClassDecorator { return target => Reflect.defineMetadata("custom:annotation", options, target); }

Define a unique metadata entry on the target.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter metadataValue

A value that contains attached metadata.

Parameter target

The target object on which to define metadata.

Parameter propertyKey

The property key for the target.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod(p) { } method(p) { } }

// property (on constructor) Reflect.defineMetadata("custom:annotation", Number, Example, "staticProperty");

// property (on prototype) Reflect.defineMetadata("custom:annotation", Number, Example.prototype, "property");

// method (on constructor) Reflect.defineMetadata("custom:annotation", Number, Example, "staticMethod");

// method (on prototype) Reflect.defineMetadata("custom:annotation", Number, Example.prototype, "method");

// decorator factory as metadata-producing annotation. function MyAnnotation(options): PropertyDecorator { return (target, key) => Reflect.defineMetadata("custom:annotation", options, target, key); }

Deletes the metadata entry from the target object with the provided key.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Returns

true if the metadata entry was found and deleted; otherwise, false.

Example 1

class Example { }

// constructor result = Reflect.deleteMetadata("custom:annotation", Example);

Deletes the metadata entry from the target object with the provided key.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Parameter propertyKey

The property key for the target.

Returns

true if the metadata entry was found and deleted; otherwise, false.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod(p) { } method(p) { } }

// property (on constructor) result = Reflect.deleteMetadata("custom:annotation", Example, "staticProperty");

// property (on prototype) result = Reflect.deleteMetadata("custom:annotation", Example.prototype, "property");

// method (on constructor) result = Reflect.deleteMetadata("custom:annotation", Example, "staticMethod");

// method (on prototype) result = Reflect.deleteMetadata("custom:annotation", Example.prototype, "method");

Gets the metadata value for the provided metadata key on the target object or its prototype chain.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Returns

The metadata value for the metadata key if found; otherwise, undefined.

Example 1

class Example { }

// constructor result = Reflect.getMetadata("custom:annotation", Example);

Gets the metadata value for the provided metadata key on the target object or its prototype chain.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Parameter propertyKey

The property key for the target.

Returns

The metadata value for the metadata key if found; otherwise, undefined.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod(p) { } method(p) { } }

// property (on constructor) result = Reflect.getMetadata("custom:annotation", Example, "staticProperty");

// property (on prototype) result = Reflect.getMetadata("custom:annotation", Example.prototype, "property");

// method (on constructor) result = Reflect.getMetadata("custom:annotation", Example, "staticMethod");

// method (on prototype) result = Reflect.getMetadata("custom:annotation", Example.prototype, "method");

Gets the metadata keys defined on the target object or its prototype chain.

Parameter target

The target object on which the metadata is defined.

Returns

An array of unique metadata keys.

Example 1

class Example { }

// constructor result = Reflect.getMetadataKeys(Example);

Gets the metadata keys defined on the target object or its prototype chain.

Parameter target

The target object on which the metadata is defined.

Parameter propertyKey

The property key for the target.

Returns

An array of unique metadata keys.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod(p) { } method(p) { } }

// property (on constructor) result = Reflect.getMetadataKeys(Example, "staticProperty");

// property (on prototype) result = Reflect.getMetadataKeys(Example.prototype, "property");

// method (on constructor) result = Reflect.getMetadataKeys(Example, "staticMethod");

// method (on prototype) result = Reflect.getMetadataKeys(Example.prototype, "method");

Gets the metadata value for the provided metadata key on the target object.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Returns

The metadata value for the metadata key if found; otherwise, undefined.

Example 1

class Example { }

// constructor result = Reflect.getOwnMetadata("custom:annotation", Example);

Gets the metadata value for the provided metadata key on the target object.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Parameter propertyKey

The property key for the target.

Returns

The metadata value for the metadata key if found; otherwise, undefined.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod(p) { } method(p) { } }

// property (on constructor) result = Reflect.getOwnMetadata("custom:annotation", Example, "staticProperty");

// property (on prototype) result = Reflect.getOwnMetadata("custom:annotation", Example.prototype, "property");

// method (on constructor) result = Reflect.getOwnMetadata("custom:annotation", Example, "staticMethod");

// method (on prototype) result = Reflect.getOwnMetadata("custom:annotation", Example.prototype, "method");

Gets the unique metadata keys defined on the target object.

Parameter target

The target object on which the metadata is defined.

Returns

An array of unique metadata keys.

Example 1

class Example { }

// constructor result = Reflect.getOwnMetadataKeys(Example);

Gets the unique metadata keys defined on the target object.

Parameter target

The target object on which the metadata is defined.

Parameter propertyKey

The property key for the target.

Returns

An array of unique metadata keys.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod(p) { } method(p) { } }

// property (on constructor) result = Reflect.getOwnMetadataKeys(Example, "staticProperty");

// property (on prototype) result = Reflect.getOwnMetadataKeys(Example.prototype, "property");

// method (on constructor) result = Reflect.getOwnMetadataKeys(Example, "staticMethod");

// method (on prototype) result = Reflect.getOwnMetadataKeys(Example.prototype, "method");

Gets a value indicating whether the target object or its prototype chain has the provided metadata key defined.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Returns

true if the metadata key was defined on the target object or its prototype chain; otherwise, false.

Example 1

class Example { }

// constructor result = Reflect.hasMetadata("custom:annotation", Example);

Gets a value indicating whether the target object or its prototype chain has the provided metadata key defined.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Parameter propertyKey

The property key for the target.

Returns

true if the metadata key was defined on the target object or its prototype chain; otherwise, false.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod(p) { } method(p) { } }

// property (on constructor) result = Reflect.hasMetadata("custom:annotation", Example, "staticProperty");

// property (on prototype) result = Reflect.hasMetadata("custom:annotation", Example.prototype, "property");

// method (on constructor) result = Reflect.hasMetadata("custom:annotation", Example, "staticMethod");

// method (on prototype) result = Reflect.hasMetadata("custom:annotation", Example.prototype, "method");

Gets a value indicating whether the target object has the provided metadata key defined.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Returns

true if the metadata key was defined on the target object; otherwise, false.

Example 1

class Example { }

// constructor result = Reflect.hasOwnMetadata("custom:annotation", Example);

Gets a value indicating whether the target object has the provided metadata key defined.

Parameter metadataKey

A key used to store and retrieve metadata.

Parameter target

The target object on which the metadata is defined.

Parameter propertyKey

The property key for the target.

Returns

true if the metadata key was defined on the target object; otherwise, false.

Example 1

class Example { // property declarations are not part of ES6, though they are valid in TypeScript: // static staticProperty; // property;

static staticMethod(p) { } method(p) { } }

// property (on constructor) result = Reflect.hasOwnMetadata("custom:annotation", Example, "staticProperty");

// property (on prototype) result = Reflect.hasOwnMetadata("custom:annotation", Example.prototype, "property");

// method (on constructor) result = Reflect.hasOwnMetadata("custom:annotation", Example, "staticMethod");

// method (on prototype) result = Reflect.hasOwnMetadata("custom:annotation", Example.prototype, "method");

A default metadata decorator factory that can be used on a class, class member, or parameter.

Parameter metadataKey

The key for the metadata entry.

Parameter metadataValue

The value for the metadata entry.

Returns

A decorator function.

Remarks

If metadataKey is already defined for the target and target key, the metadataValue for that key will be overwritten.

Example 1

// constructor @Reflect.metadata(key, value) class Example { }

// property (on constructor, TypeScript only) class Example { @Reflect.metadata(key, value) static staticProperty; }

// property (on prototype, TypeScript only) class Example { @Reflect.metadata(key, value) property; }

// method (on constructor) class Example { @Reflect.metadata(key, value) static staticMethod() { } }

// method (on prototype) class Example { @Reflect.metadata(key, value) method() { } }