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@toreda/strong-types

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Readme

`@toreda/strong-types`

Guaranteed types with validation in 1 line of code. Improve code quality & reliability while writing fewer lines of code.

What does it do?

import {Int, makeInt} from '@toreda/strong-types';
//  int with initial value 10.
const int = makeInt(10);
// Prints 10. It always return an int.
console.log(int());

// Set the value
int(11);
// Prints 11.
console.log(int());

// Won't set the value - it's not an int.
int(null);
int(undefined);
int(3.33);
int({});

// Prints 11
console.log(int());

Basic Usage
Built-in Types - StrongMap - StrongArray - Bool - Double - Int - StrongString - UInt
Custom Types - Validators
```
[**Package**](#package)
```
- Build
- Testing
- License

Using `StrongType`

Each built-in type exports a type and make function. The below examples use Int but work the same using: StrongArray, Bool, Double, Int, StrongString, and UInt.

Instantiate with initial value

import {Int, makeInt} from '@toreda/strong-types';

const initial = 11;
const fallback = 55;
const int = makeInt(initial, fallback);

// Returns 11 - initial value was 11.
const value = int();

Instantiate without initial value

import {Int, makeInt} from '@toreda/strong-types';

const fallback = 919;
const int = makeInt(null, fallback);

// value is 919 - initial value was null, so fallback was
// returned instead to maintain the function's return type guarantee.
const value = int();

Get with Fallback

get(fallback: T): T Call container.get(fallback) when a per-call fallback is preferred instead of the container's default fallback.

import {Int, makeInt} from '@toreda/strong-types';
const int = makeInt(null, 555);

const fallback = 331;
// Prints 331 (fallback) instead of 555 (container default fallback).
console.log(value.get(fallback));

GetNull

getNull(): T | null Call container.getNull() to the current value, even if null. Value will never be undefined and will always return either null, or a value of container's generic type T.

NOTE: getNull DOES NOT take a fallback argument and will not return the container's default fallback. It always returns value (null or StrongType<T>).

import {Int, makeInt} from '@toreda/strong-types';

const fallback = 919;
const int = makeInt(null, fallback);

// Prints null. Default fallback is not used for `getNull` calls.
console.log(int.getNull());

Set Value

import {Int, makeInt} from '@toreda/strong-types';

const initial = 331;
const fallback = 400;
const int = makeInt(initial, fallback);

// value is 331 - the int's initial value.
const value = int();

// Set int to a new value.
int(555);

// value is 555 - the value we updated int to.
const value = int();

Set `null`

import {Int, makeInt} from '@toreda/strong-types';

const initial = 414;
const fallback = 500;
const int = makeInt(initial, fallback);

// value is 414 - the int's initial value.
const value = int();


// Set value to null.
int(null);

// value is 500 - Fallback returned because value was null.
const value = int();

Reset Value

Call myContainer.reset() to reset value without creating a new StrongType container. Default Fallback will not be reset. Useful for unit testing and serverless environments where the previous container value or state is unknown.

import {Int, makeInt} from '@toreda/strong-types';

const initial = 515;
const fallback = 600;
const int = makeInt(initial, fallback);

// value is 515 (the initial value).
const value = int();

// Reset container value
int.reset();

// Prints 600 (fallback). value was reset to null,
// fallback was returned to maintain return type guarantee.
console.log(int());

Validation

StrongType containers validate value inputs before setting. Bad values are ignored and will not cause a throw. Each built-in container type provides specific guarantees for which values are allowed.

import {Int, makeInt} from '@toreda/strong-types';
const int = makeInt(50, 100);

// success is false.
// container.value is still it's initial value 50 because 1.5 is not an int.
// Int does not round or truncate non-integers. They are simply ignored.
const success = int(1.5);

Supported Types

StrongArray, arrays
Bool, booleans (strict)
Double, doubles
Int, integers
UInt, unsigned integers
StrongString - strings

Using `StrongMap`

Creating and using a StrongMap class.

import {StrongMap, Int, StrongString, makeInt, makeString} from '@toreda/strong-types';


export class SomeConfig extends StrongMap {
    public readonly counter: Int;
    public readonly name: StrongString;

    constructor(json: any) {
        super();
        this.counter = makeInt(0, 0);
        this.name = makeString(null, 'TreeBeard');
        this.parse(json);
    }
}


// Use it
const myConfig = new SomeConfig();

// Prints '0'
console.log(myConfig.counter());

// Prints 'Treebeard'
console.log(myConfig.name());

Creating a StrongMap and loading values from JSON

import {StrongMap, StringInt, StrongString, makeInt, makeString} from '@toreda/strong-types';

export class SomeConfig extends StrongMap {
    public readonly counter: Int;
    public readonly name: StrongString;

    constructor(json?: any) {
        super();
        this.counter = makeInt(0, 0);
        this.name = makeString(null, 'TreeBeard');
        this.parse(json);
    }
}

const myJSON = {
    'counter': 99,
    'name': 'Sauron'
};

// Load the recursively parse a JSON object.
const myConfig = new SomeConfig(myJSON);

// Prints 99 - myJSON.counter was loaded into SomeConfig.counter at instantiation.
console.log(myConfig.counter());

// Prints 'Sauron' - myJSON.name was loaded into SomeConfig.name at instantiation.
console.log(myConfig.name());

Converting a StrongMap to a json object

import {StrongMap, StringInt, StrongString, makeInt, makeString} from '@toreda/strong-types';

export class SomeConfig extends StrongMap {
    public readonly counter: Int;
    public readonly name: StrongString;

    constructor(json?: any) {
        super();
        this.counter = makeInt(0, 0);
        this.name = makeString(null, 'TreeBeard');
        this.parse(json);
    }
}

const myJSON = {
    'counter': 99,
    'name': 'Sauron'
};

// Create the StrongMap with myJSON data
const myConfig = new SomeConfig(myJSON);

// Change a value in the StrongMap
myConfig.name('Gandalf');

// {counter: 99, name: 'Gandalf'}
const configAsJSON = myConfig.jsonify();

`StrongArray`

Import

import {StrongArray, makeArray} from '@toreda/strong-types';

Accepted Values

Arrays holding any type (e.g. T[])
Accepts empty arrays (e.g. [])

`Bool`

Import

import {Bool, makeBoolean} from '@toreda/strong-types';

Accepted Values

Strict booleans: true or false only.
No type coercion (e.g. 1 or 0 will be rejected).

`Double`

Import

import {Double, makeDouble} from '@toreda/strong-types';

Accepted Values

number values between and including Number.MIN_VALUE and Number.MAX_VALUE.
Rejects NaN values.

`Int`

Import

import {Int, makeInt} from '@toreda/strong-types';

Accepted Values

number values between and including Number.MIN_VALUE and Number.MAX_VALUE.
NaN values are rejected.

`StrongString`

Import

import {StrongString, makeString} from '@toreda/strong-types';

Accepted Values

string values of any valid length.

`UInt`

Import

import {UInt, makeUInt} from '@toreda/strong-types';

Accepted Values

Integers between and including 0 and Number.MAX_SAFE_INTEGER.
Rejects numbers which are non-integers (e.g. 1.5)
Rejects NaN
Rejected negative integers (e.g. -22).

Custom Types

Each built-in type like Int and UInt are helper functions wrapping Strong<T>. They also apply validators which guarantee the Strong<T> value behaves as expected. While built-ins are provided for convenience, you can create custom types with your own validators.

Instantiate `Strong<T>`

import {Strong, makeStrong} from '@toreda/strong-types';

export type MyOwnType = {
    id: string | null;
    name: string | null;
};

const initial: MyOwnType = {
    id: 'hello',
    name: 'my name is'
};

const fallback: MyOwnType = {
    id: null,
    name: null
};

const myObj = makeStrong<MyOwnType>(initial, fallback);

Validators

Install

Install @toreda/strong-types directly from NPM or clone the Github repo.

Install using Yarn (preferred)

Open a shell (or console).
Navigate to the the StrongTypes root project folder.
Enter the following commands in order. Wait for each to complete before typing the next.

yarn

Install using NPM

Open a shell (or console).
Navigate to the the StrongTypes root project folder.
Enter the following commands in order. Wait for each to complete before typing the next.

npm install

Run Unit Tests

Install or clone StrongTypes (see above).

StrongTypes tests are written with Jest which is also a project dev dependency.

Installing jest is not required after project dependencies are installed (see above).

yarn test

Build from source

The next steps are the same whether you installed the package using NPM or cloned the repo from Github.

Build with Yarn

Enter the following commands in order from the StrongTypes root project folder.

yarn build

Build with NPM

Enter the following commands in order from the StrongTypes root project folder.

npm run-script build