lodash-decorators

lodash-decorators

Method Decorators for lodash functions.

• Install
• Usage
  • With Arguments
    • Example
  • Without Arguments
    • Example
  • Partials
    • Example
  • Composition
    • Example
  • Instance Decorators
  • Mixin
    • Example
  • Attempt
    • Example
  • Bind
    • Example
    • Example
  • v4 Breaking Changes
    • Not all decorators can be applied to or forced on getters/setters.
    • No longer force instance decorator onto prototype
    • Curry is now an instance decorator
    • Removal of extensions and validation package
    • Other breaking changes
  • v4 Improvements

Install

npm install --save lodash-decorators

Usage

For more in depth documentation please visit Lodash

Decorators are exported as both start case and lower case.

import { Debounce } from 'lodash-decorators';

is the same as

import { debounce } from 'lodash-decorators';

They can also be imported directly.

import Debounce from 'lodash-decorators/debounce';

With Arguments

Many of the lodash decorators can contain arguments.

• Debounce
• DebounceAll
• Throttle
• ThrottleAll
• Memoize
• MemoizeAll
• After
• AfterAll
• Before
• BeforeAll
• Ary
• Curry
• CurryAll
• CurryRight
• CurryRightAll
• Rest
• Partial
• PartialRight
• Wrap
• Flow
• FlowRight
• Delay
• Defer
• Bind
• BindAll
• OverArgs
• Rearg
• Mixin
• Attempt

Example

import { After, Debounce, Memoize, Curry } from 'lodash-decorators'

class Person {
  constructor(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  }

  @After(3)
  @Debounce(100)
  getFullName() {
    return `${this.firstName} ${this.lastName}`
  }

  @Curry(2)
  @Memoize()
  doSomeHeavyProcessing(arg1, arg2) {
  }
}

Without Arguments

Some decorators don't take any arguments at all.

• Once
• Spread
• Negate
• Tap

Example

import { Once } from 'lodash-decorators'

class person {
  constructor(firstname, lastname) {
    this.firstname = firstname;
    this.lastname = lastname;
  }

  @Once
  getfullname() {
    return `${this.firstname} ${this.lastname}`
  }

  @Tap
  popIt(list) {
    list.pop();
  }
}

const person = new Person();

person.popIt([1, 2, 3]); //=> [1, 2]

Partials

Some decorators work slightly differently than you would expect them to work than lodash.

• Partial
• PartialRight
• Wrap

These can take a Function as their first argument or a String. If the argument is a String then a Function is resolved from the current object.

Example

import { Partial } from 'lodash-decorators'

class Person {
  constructor(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  }

  getName(type) {
    return type === 'firstName' ? this.firstName : this.lastName
  }

  @Partial('getName', 'firstName')
  getFirstName() {}

  @Partial('getName', null)
  getLastName() {}

  @Wrap('getName')
  getUpperCaseName(fn) {
    return fn().toUpperCase();
  }
}

const person = new Person('Joe', 'Smith');

person.getFirstName(); // 'Joe'
person.getLastName(); // 'Smith'
person.getUpperCaseName(); // JOE SMITH

Composition

You can use methods like compose and flow similiar to partials. The arguments are resolved the same way partials are resolved.

Example

import { Flow } from 'lodash-decorators'
import { kebabCase } from 'lodash';

class Person {
  constructor(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  }

  getName() {
    return `${this.firstName} ${this.lastName}`;
  }

  @Flow('getName', kebabCase)
  logName(name) {
    console.log(name);
  }
}

const person = new Person('Joe', 'Smith');

person.logName(); // joe-smith

Instance Decorators

Normally decorators are applied to the prototype method of the class you are working with, but with some of these decorators that is not the desired behavour. These decorators are applied at the instance level.

• Debounce
• Throttle
• Memoize
• After
• Before
• Curry
• CurryRight

Mixin

You can mixin methods into a class by using the Mixin decorator.

Example

import { Mixin } from 'lodash-decorators';

const MyOtherApi = {
  someCoolMethod() {
    // Do something cool
  }
};

@Mixin(MyOtherApi)
class Person {}

Person.prototype.someCoolMethod === MyOtherApi.someCoolMethod; // => true

Attempt

You can wrap a method in a lodash attempt method.

Example

import { Attempt } from 'lodash-decorators';

class Person {
  @Attempt()
  throwAnError() {
    throw new Error();
  }

  @Attempt()
  doNotThrowAnError() {
    return '0_o';
  }
}

const person = new Person();

let result = person.throwAnError();

result instanceof Error; // => true

result = person.doNotThrowAnError();

result === '0_o'; // => true

Bind

Bind takes arguments based on lodash's bind and binds the Function to the current instance object.

Example

import { Bind } from 'lodash-decorators'

class Person {
  constructor(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  }

  @Bind()
  getName() {
    return `${this.firstName} ${this.lastName}`;
  }

  // It can also function as a partial
  @Bind('Joe')
  getUpperCaseName(name) {
    return name.toUpperCase();
  }
}

const person = new Person('Joe', 'Smith');

person.getName.call(null); // Joe Smith
person.getUpperCaseName(); // JOE

You can also bind entire classes with bindAll or bind.

Example

import { BindAll } from 'lodash-decorators'

@BindAll()
class Person {
  constructor(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  }

  getName() {
    return `${this.firstName} ${this.lastName}`;
  }
}

const person = new Person('Joe', 'Smith');

person.getName.call(null); // Joe Smith

v4 Breaking Changes

Version 4 is a rewrite of the library and has many breaking changes.

Not all decorators can be applied to or forced on getters/setters.

Only certain decorators make sense to be applied to getters/setters. Before you could specify the target of the decorator like debounce.set(15). This behavior is removed and decorators that make sense to apply to getters/setters are configured to be applied to methods and either the getter or the setter. For example:

class MyClass {
  // This only gets applied to the setter as it doesn't make sense to apply it to the getter.
  @Debounce(1000) 
  get value() {
    return this._value;
  }

  set value(val) {
    this._value = val;
  }

  @Debounce(15)
  fn() {}
}

This keeps the API cleaner and doesn't require the developer to know how the decorator applies to the descriptor.

No longer force instance decorator onto prototype

There is no longer a Proto decorator attached to instance decorators. Most instance decorators now have a counterpart that applies to the prototype instead of the instance. Debounce.Proto() is now DebounceAll().

Curry is now an instance decorator

The curry decorator is now an instance decorator in order to keep the calling context consistent. The original function before being curried is bound to the instance. You can apply curry to the prototype by using CurryAll().

Removal of extensions and validation package

All extensions like enumerable have been removed in favor of core-decorators. There may be some slight over lap like debounce and throttle. Fair warning, instance decorators may not play nice with other implementations of instance decorators.

We want to keep lodash decorators focused specifically on lodash specific functions.

Other breaking changes

• Attempt now takes an argument to line up with lodash API.
• Bind used on a class no longer delegates to BindAll. Use BindAll instead.

v4 Improvements

• Instance and prototype decorators can be in any order.
• Ships with TypeScript typings.
• Predictable performance.
• Improvements to Bind decorator.
• Improved API for decorator factory.
• More and better unit tests.
• Better performance with instance decorators.
• Single imports with import { Debounce } from 'lodash-decorators/debounce';

Author: Steven Sojka MIT Licensed