lodash-decorators
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ES7 Decorators for lodash functions.
The decorator proposal is still in quite a bit of flux. There will most likely be breaking changes as the spec changes. These will be reflected in major releases (2.0.0).
npm install --save lodash-decorators
For more in depth documentation please visit Lodash
Many of the lodash decorators can contain arguments.
debouncethrottlememoizeafterbeforearycurrycurryRightrestParampartialpartialRightwrapcomposeflowflowRightbackflowdelaydeferbindbindAllmodArgsmixinimport { 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} ${this.lastName}`
}
@curry(2)
@memoize()
doSomeHeavyProcessing(arg1, arg2) {
}
}
Some decorators don't take any arguments at all.
oncespreadreargnegatetapattemptimport { once } from 'lodash-decorators'
class Person {
constructor(firstName, lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
@once
getFullName() {
return `${this.firstName} ${this.lastName}`
}
@tap
popIt(list) {
list.pop();
}
}
const person = new Person();
person.popIt([1, 2, 3]); //=> [1, 2]
Some decorators work slightly differently than you would expect them to work than lodash.
partialpartialRightwrapThese can take a Function as their first argument or a String.
If the argument is a String then a Function is resolved from
the current object.
import { partial } from 'lodash-decorators'
class Person {
constructor(firstName, lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
getName(type) {
return type === 'firstName' ? this.firstName : this.lastName
}
@partial('getName', 'firstName')
getFirstName() {}
@partial('getName', null)
getLastName() {}
@wrap('getName')
getUpperCaseName(fn) {
return fn().toUpperCase();
}
}
const person = new Person('Joe', 'Smith');
person.getFirstName(); // 'Joe'
person.getLastName(); // 'Smith'
person.getUpperCaseName(); // JOE SMITH
You can use methods like compose and flow similiar to
partials. The arguments are resolved the same way partials
are resolved.
import { compose } from 'lodash-decorators'
import { kebabCase } from 'lodash';
class Person {
constructor(firstName, lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
getName() {
return `${this.firstName} ${this.lastName}`;
}
@compose(kebabCase, 'getName')
logName(name) {
console.log(name);
}
}
const person = new Person('Joe', 'Smith');
person.logName(); // joe-smith
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.
debouncethrottlememoizeafterbeforeNote: Due to the nature of how instance decorators work they MUST be processed after all prototype decorators in the decorator chain. There isn't a graceful way to get around this currently. More or less instance decorators are kind of a hack and experimental.
class Person {
@curry(2) // <= prototype decorator
@debounce(100) // <= instance decorator
getName() {} //=> Throws an error. (╯°□°）╯︵ ┻━┻
@debounce(100) // <= instance decorator
@curry(2) // <= prototype decorator
getName2() {} //=> All is well :)
}
Most decorators can be applied directly to getter and setter methods.
import { once, compose } from 'lodash-decorators'
import _ from 'lodash';
function alwaysArray(value) {
return Array.isArray(value) ? value : _.isUndefined(value) ? [] : [value];
}
class Person {
constructor() {}
@once.get
get names() {
return this.nameList.join(' ');
}
@compose.set(alwaysArray)
set names(names) {
this.nameList = names;
}
}
const person = new Person();
// nameList will always be an array.
person.names = undefined; //=> []
person.names = 'Joe'; //=> ['Joe']
person.names = ['Jim']; //=> ['Jim']
.get?The decorator has no way to tell whether you are applying the decorator to the getter or setter (when both are provided). The decorator just receives the descriptor which has both values provided and no way to distinguish which one you are provided which decorator to.
@once.get uses a form of the decorator that explicitly applies to the getter method.
@once.set uses a form of the decorator that explicitly applies to the setter method.
Use at you're own risk...
You can mixin methods into a class by using the Mixin decorator.
import { mixin } from 'lodash-decorators';
const MyOtherApi = {
someCoolMethod() {
// Do something cool
}
};
@mixin(MyOtherApi)
class Person {}
Person.prototype.someCoolMethod === MyOtherApi.someCoolMethod; // => true
You can wrap a method in a lodash attempt method.
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 takes arguments based on lodash's bind and binds the Function to
the current instance object.
Known Issue: When using bind on a single method the bind decorator MUST come last
in the chain of decorators. There is no graceful solution for this currently. You can always
use @bindAll('fn') on the class and only include the functions you want to include.
import { bind } from 'lodash-decorators'
class Person {
constructor(firstName, lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
@bind()
getName() {
return `${this.firstName} ${this.lastName}`;
}
// It can also function as a partial
@bind('Joe')
getUpperCaseName(name) {
return name.toUpperCase();
}
}
const person = new Person('Joe', 'Smith');
person.getName.call(null); // Joe Smith
person.getUpperCaseName(); // JOE
You can also bind entire classes with bindAll or bind.
Note: Using @bind() on a class delegates to the @bindAll() implemenation.
import { bind } from 'lodash-decorators'
@bindAll()
class Person {
constructor(firstName, lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
getName() {
return `${this.firstName} ${this.lastName}`;
}
}
const person = new Person('Joe', 'Smith');
person.getName.call(null); // Joe Smith
You can force an instance decorator to apply to the prototype instead of the instance.
import { throttle } from 'lodash-decorators';
class Person {
@throttle(1000)
doStuff() {}
@throttle.proto(1000)
doStuffMore() {}
}
const person = new Person();
const person2 = new Person();
person.doStuff(); //=> Both are called
person2.doStuff();
person.doStuffMore();
person2.doStuffMore();
// Only one of these methods is actual invoked because throttle is applied to the prototype method
// and not the instance method.
Extensions are decorators that aren't necessarily Lodash functions, but use Lodash under the hood. They provided some more basic utilities not found in Lodash;
deprecatedwritableconfigurablereturnsArgenumerablenonenumerable -> enumerable(false)nonconfigurable -> configurable(false)readonly -> writable(false)Warns when a deprecated class is istantiated or a deprecated class method is invoked. You can also modify the deprecated behaviour by swapping out the method and class actions.
import { deprecated } from 'lodash-decorators/extensions'
// This is applied globally.
deprecated.methodAction = fn => console.log(`Don't use ${fn.name}!`);
@deprecated
class Person {
constructor() {}
}
class OtherPerson {
@deprecated
fn() {}
}
let person = new Person(); //=> Warning!
let otherPerson = new OtherPerson();
otherPerson.fn(); //=> Don't use fn!
The validate module contains decorators that can validate function arguments and return value.
These can be found in src/validate
Author: Steven Sojka MIT Licensed
FAQs
A collection of decorators using lodash at it's core.
The npm package lodash-decorators receives a total of 45,024 weekly downloads. As such, lodash-decorators popularity was classified as popular.
We found that lodash-decorators demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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