type-guard performs a runtime check that guarantees the type and value of properties in some scopes.

🚀 Node.js ready for launch.

🚀 Angular ready for launch.

In a Domain Driven Design approach, it is very useful to check constraints on Domain Entity and ValueType properties.

It relies on Tyr to:

1. Call one of the seven specific Guards like string() or number().
2. Call chained rule checkers.
3. Return a GuardResult instance containing the reason for the failure of the guard, or a success.

It also relies on GuardResultBulk to manage multiple Tyr invocations:

• Combine and return the first GuardResult instance in failure, or only a GuardResult instance in success.
• Stack and return all GuardResult instances in failure, or only a GuardResult instance in success.

1. Installation
2. Basic Usage
   • Guard Options
3. Tyr
   • array()
   • boolean()
   • class()
   • dateString()
   • nil()
   • number()
   • string()
4. GuardResultBulk
   • add()
   • combine()
   • stack()
5. Codex
6. TypeDoc
7. Changelog
8. The true story
9. Maintainer
10. License

npm install @xtitusx/type-guard

In order to check and return a GuardResult instance, just invoke Tyr, call a specific Guard, and finish by calling guard(propertyValue: unknown, propertyName?: string) method which contains the property value and optionaly a property name.

• A simple type property check:

Tyr.string().guard("foo");

• Multiple chained rule checkers:

Tyr.string().isAlpha().contains('foo').hasMaxLength(100).isTrimmed('left').guard("Lorem ipsum foo");

Tyr.number().isMultiple(2).isMultiple(3).isMultiple(4).guard(12);

• A fast validation returning simply a boolean:

Tyr.number().isBetween(10, 20).isEven().guard(14).isSuccess();

• A thrown exception with a GuardResult instance message:

 const guardResult = Tyr.dateString().isIso8601Date().guard('29-02-2021');
if (!guardResult.isSuccess()) {
    throw new Error(guardResult.getMessage());
}

Tyr.array(), Tyr.dateString(), Tyr.number(), and Tyr.string() methods expect an IGuardOptions object optionaly:

export interface IGuardOptions {
    /**
     * A single type of rule, the last called in the chain, is retained by the guard.
     * @defaultValue false
     */
    overriding?: boolean;
}

const stringGuard = Tyr.string({ overriding: true }).isTrimmed('right').hasMinLength(2).hasMaxLength(100);

const guardResult1 = stringGuard.contains('dummy').guard('Lorem Ipsum is simply dummy text');

const guardResult2 = stringGuard
    .contains('random')
    .guard('Contrary to popular belief, Lorem Ipsum is not simply random text');

Adds GuardResult instance(s) in bulk:

const guardResultBulk = new GuardResultBulk().add(Tyr.string().equals('foo').guard('foo'));

Returns either the first fail in bulk, or only one success:

const guardResult = new GuardResultBulk()
    .add([
        Tyr.array().hasMinSize(2).contains("foo").guard(['foo', 'bar'],
        Tyr.string().equals('foo').guard('foo'),
        Tyr.number().isBetween(10, 20).isEven().guard(14),
    ])
    .combine();

Returns all fails in bulk, or only one success:

const guardResult = new GuardResultBulk()
    .add([
        Tyr.array().hasMinSize(2).contains("foo").guard(['foo', 'bar'],
        Tyr.string().equals('foo').guard('foo'),
        Tyr.number().isBetween(10, 20).isEven().guard(14),
    ])
    .stack();

Refer to the Codex to directly access Enums containing some ISO values:

GitHub HTML Preview

See information about breaking changes and release notes here.

Once upon a time there was a forgotten kingdom, lost in the far north, called TypGard 🌈.

This kingdom was populated by two complementary tribes living in harmony: the Backings and the Frontkings. Two other tribes, constantly at war, the Vikings and the Nanokings quarreled in the mountains 🗻, but we will not discuss them in this story ...

The Backings were a people of craftsmen: miners 💎, blacksmiths 🔨, loggers, lumberjacks. The Frontkings were a tribe skilled in the arts, including body painting 🎭 and storytelling 🎻.

After each daily thing ☕, Frontking's skalds often swapped the tale of one or two sagas against the essential goods produced by the Backings.

And all this little small world lived in cooperation and peace, until the day, when curious foreigners from the south, tried to sow trouble, and divide this beautiful and well-ordered kingdom 🐍. The northerners, not understanding their language, decided to simply name these invaders the sons of Julius, or Jsøns in Old Nordic language.

The Jsøns were devious and manipulative, and the Northerners never knew if they were telling them the truth .

Fortunately, they could rely on Tyr, the deity of order and law, to gauge each suspected Jsøn, and validate his claims.

Tyr was accompanied by seven guards, each representing an aspect of the order ...

• xtitusx - Benjamin Tussac (author)

MIT License

Copyright (c) 2021 Benjamin Tussac

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.