JarCastingdecko 
A concise implementation of the three most useful decorators:
@bind: make the value ofthisconstant within a method@debounce: throttle calls to a method@memoize: cache return values based on arguments
Decorators 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.
Installation
Available on npm:
npm i -S decko
Usage
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();
License
MIT