@geraintguan/ts-std-lib

API Reference

A practical and pragmatic standard library for TypeScript (and JavaScript).

Installation

NPM

npm install -S @geraintguan/ts-std-lib

PNPM

pnpm add @geraintguan/ts-std-lib

Usage

Data Structures

HashMap

API Reference

Implementation of a key-value map that allows you to customise the way keys are stored by using a custom hashing function.

Example: HashMap of ISO8601 Date String keys

One useful example is using a HashMap that accepts Date objects as keys but storing them as their ISO8601 Date Strings.

import * as Std from "@geraintguan/ts-std-lib";

const map = Std.Data.HashMap.emptyWithCustomHash<Date, number, string>({
  hash(date) {
    data.toISOString();
  },
});

const today = new Date("2024-11-01T12:00:00.000Z");
const tomorrow = new Date("2024-11-02T12:00:00.000Z");

map.set(today, 2);
map.set(tomorrow, 3);

[...map.keys()]; // => [
//   "2024-11-01T12:00:00.000Z",
//   "2024-11-02T12:00:00.000Z"
// ]

DefaultMap

API Reference

Implementation of a key-value map that allows you to customise the way keys are stored by using a custom hashing function and specify either a value or value generator function that will be returned when trying to access non-existant keys.

Example: DefaultMap of ID of documents with timestamp that defaults to current date and time

import * as Std from "@geraintguan/ts-std-lib";

type Document = {
  id: string;
};

const map = Std.Data.DefaultMap.emptyWithCustomHash<Document, Date, string>({
  defaultValue: {
    type: "function",

    value() {
      return new Date(),
    }
  },
  hash(document) {
    return document.id;
  },
});

const documentA = { id: "document-a" };
const documentB = { id: "document-b" };
const documentC = { id: "document-c" };

map.set(documentA, new Date("2020-01-01T00:00:00.000Z"));
map.set(documentB, new Date("2021-01-01T00:00:00.000Z"));

map.get(documentA).toISOString() // => "2020-01-01T00:00:00.000Z"
map.get(documentB).toISOString() // => "2021-01-01T00:00:00.000Z"
map.get(documentC).toISOString() // => new Date().toISOString()

[...map.keys()] // => [
//   "document-a",
//   "document-b",
//   "document-c",
// ]

Utility Functions

constant()

API Reference

Creates a function that always returns a specific value.

Example

import * as Std from "@geraintguan/ts-std-lib";

const nine = Std.constant(9);

nine(); // => 9
nine(); // => 9
nine(); // => 9

identity()

API Reference

Creates a function that always returns the value given to it as an argument.

Example

import * as Std from "@geraintguan/ts-std-lib";

[true, false, true].filter(Std.identity); // => [
//   true,
//   true
// ]