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Decko is a collection of decorators for JavaScript/TypeScript that simplify common patterns such as binding methods to their instances, memoizing function results, and throttling or debouncing function calls.
Bind
The @bind decorator ensures that the method is always called with the correct 'this' context, even if it's extracted from the instance.
class MyClass {
@bind
myMethod() {
console.log(this);
}
}
const instance = new MyClass();
const method = instance.myMethod;
method(); // Logs the instance of MyClass
Memoize
The @memoize decorator caches the result of a function call and returns the cached result when the same inputs occur again, avoiding redundant computations.
class MyClass {
@memoize
computeExpensiveValue(input) {
console.log('Computing...');
return input * 2;
}
}
const instance = new MyClass();
console.log(instance.computeExpensiveValue(2)); // Logs 'Computing...' and then 4
console.log(instance.computeExpensiveValue(2)); // Logs 4 without 'Computing...'
Debounce
The @debounce decorator ensures that the decorated function is only called once within the specified time frame, even if it's triggered multiple times.
class MyClass {
@debounce(300)
handleResize() {
console.log('Resized!');
}
}
const instance = new MyClass();
window.addEventListener('resize', () => instance.handleResize());
Throttle
The @throttle decorator ensures that the decorated function is called at most once within the specified time frame, even if it's triggered multiple times.
class MyClass {
@throttle(300)
handleScroll() {
console.log('Scrolled!');
}
}
const instance = new MyClass();
window.addEventListener('scroll', () => instance.handleScroll());
Core-decorators is a library that provides a set of decorators for common patterns in JavaScript/TypeScript, such as @autobind, @memoize, @debounce, and @throttle. It offers similar functionality to decko but with a broader set of decorators.
Lodash-decorators is a library that provides decorators for lodash functions, including @debounce, @throttle, and @memoize. It integrates lodash's powerful utility functions with the decorator syntax, offering a more extensive set of utilities compared to decko.
Typescript-decorators is a library that provides a collection of decorators for TypeScript, including method decorators like @autobind, @debounce, and @throttle. It is similar to decko but is specifically designed for TypeScript.
A concise implementation of the three most useful decorators:
@bind
: make the value of this
constant within a method@debounce
: throttle calls to a method@memoize
: cache return values based on argumentsDecorators help simplify code by replacing the noise of common patterns with declarative annotations. Conversely, decorators can also be overused and create obscurity. Decko establishes 3 standard decorators that are immediately recognizable, so you can avoid creating decorators in your own codebase.
💡 Tip: decko is particularly well-suited to Preact Classful Components.
💫 Note:
- For Babel 6+, be sure to install babel-plugin-transform-decorators-legacy.
- For Typescript, be sure to enable
{"experimentalDecorators": true}
in your tsconfig.json.
Available on npm:
npm i -S decko
Each decorator method is available as a named import.
import { bind, memoize, debounce } from 'decko';
@bind
class Example {
@bind
foo() {
// the value of `this` is always the object from which foo() was referenced.
return this;
}
}
let e = new Example();
assert.equal(e.foo.call(null), e);
@memoize
Cache values returned from the decorated function. Uses the first argument as a cache key. Cache keys are always converted to strings.
Options:
caseSensitive: false
- Makes cache keys case-insensitive
cache: {}
- Presupply cache storage, for seeding or sharing entries
class Example {
@memoize
expensive(key) {
let start = Date.now();
while (Date.now()-start < 500) key++;
return key;
}
}
let e = new Example();
// this takes 500ms
let one = e.expensive(1);
// this takes 0ms
let two = e.expensive(1);
// this takes 500ms
let three = e.expensive(2);
@debounce
Throttle calls to the decorated function. To debounce means "call this at most once per N ms". All outward function calls get collated into a single inward call, and only the latest (most recent) arguments as passed on to the debounced function.
Options:
delay: 0
- The number of milliseconds to buffer calls for.
class Example {
@debounce
foo() {
return this;
}
}
let e = new Example();
// this will only call foo() once:
for (let i=1000; i--) e.foo();
MIT
FAQs
A collection of the most useful property decorators.
We found that decko 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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