TimeMap

ECMAScript 6 Map-Like implementation with keys that have a defined timelife.

Requirements

• Node.js v12 or higher

Getting Started

This package is available in the Node Package Repository and can be easily installed with npm or yarn.

$ npm i @slimio/timemap
# or
$ yarn add @slimio/timemap

Usage example

const { strictEqual } = require("assert");
const TimeMap = require("@slimio/timemap");

const col = new TimeMap(1000);
col.on("expiration", (key, value) => {
    console.log(`col key ${key} has expired!`);
});

col.set("foo", "bar");
col.set("test", true);
strictEqual(col.has("foo"), true);

setTimeout(() => {
    col.set("hello", "world!");
    strictEqual(col.has("foo", true), true);
}, 500);

setTimeout(() => {
    strictEqual(col.has("foo"), true);
}, 500)

setTimeout(() => {
    strictEqual(col.has("foo"), false);
    strictEqual(col.has("test"), false);
    strictEqual(col.has("hello"), true);
}, 1100);

Events

TimeMap class is extended by a Node.js EventEmitter. The class can trigger several events:

event name	description
expiration	Expired key are emitted before deletion

const map = new TimeMap(100);
map.on("expiration", (key, value) => {
    console.log(`key: ${key}, value: ${value}`);
});

map.set("foo", "bar");

API

Following methods are members of TimeMap class. The type TimeMap.key is declared as follow:

type key = symbol | string | number;

constructor(timeLifeMs: number)

Create a new TimeMap Object. Take an argument which is the time that a key stay alive within the class.

const map = new TimeMap(5000);
map.set("foo", "bar"); // foo will live for the next 5,000 milliseconds

The default timeLifeMs is equal to the value of static member TimeMap.DEFAULT_TIMELIFE_MS (equal to 1000 by default).

const { strictEqual } = require("assert");

const map = new TimeMap();
strictEqual(map.timeLife, TimeMap.DEFAULT_TIMELIFE_MS);

set(key: TimeMap.key, value: any): void

Set a new key in the Collection. Inner timer will be initialized by the first key. The key must be a string or a symbol (no other primitive are accepted).

const { strictEqual } = require("assert");

const map = new TimeMap();
const sym = Symbol("foo");
map.set(sym, "bar");
strictEqual(map.get(sym), "foo");

has(key: TimeMap.key, refreshTimestamp?: boolean): boolean

Similar to Map.has method. Return true if the key exist within.

const { strictEqual } = require("assert");

const map = new TimeMap(100);
map.set("foo", "bar");
setTimeout(() => {
    strictEqual(map.has("foo", true), true);
}, 50);

setTimeout(() => {
    strictEqual(map.has("foo"), true);
}, 50);

setTimeout(() => {
    strictEqual(map.has("foo"), false);
}, 50);

delete(key: TimeMap.key): void

Delete a given key from TimeMap. The key must be a string or a symbol.

const { strictEqual } = require("assert");

const map = new TimeMap(100);
map.once("expiration", (key) => {
    strictEqual(key, "hello");
});
map.set("foo", "bar");
map.set("hello", "world");

setTimeout(() => {
    map.delete("foo");
}, 50)

get< T >(key: TimeMap.key, refreshTimestamp?: boolean): T

Get a given key from the Class. Throw an Error if the key doesn't exist in the Collection (use .has() before).

const assert = require("assert");

const map = new TimeMap(100);
map.set("foo", "bar");

assert.strictEqual(map.get("foo"), "bar");
assert.throws(() => {
    map.get("world!");
}, { name: "Error" });

clear(): void

Clear internal timer and internal data. Everything will be reset.

keys(): IterableIterator< TimeMap.key >

The keys() method returns a new Iterator object that contains the keys for each element in the TimeMap object in insertion order.

const { deepEqual } = require("assert");

const map = new TimeMap();
map.set("foo", "bar");
map.set("yo", "boo");

deepEqual(["foo", "yo"], [...map.keys()]);

Properties

All following properties are readonly

.size

The size accessor property returns the number of elements in the TimeMap.

const { strictEqual } = require("assert");

const map = new TimeMap();
map.set("foo", "bar");
strictEqual(map.size, 1);

.timeLife

The timeLife accessor property return the configured time life for keys

const { strictEqual } = require("assert");

const map = new TimeMap(2000);
strictEqual(map.timeLife, 2000);

Dependencies

This project have no dependencies.

License

MIT