enforce-unique

enforce-unique is a package that helps you ensure values are unique before you assign them.

Installation

``sh
npm install enforce-unique --save
`

Usage

Simplest usage is just providing a value. If the same value is provided before, enforce method will throw an EnforceUniqueError.

`ts
import { EnforceUniqueError, UniqueEnforcer } from 'enforce-unique';

const arrayContainsUniqueItems: number[] = [];

const uniqueEnforcer = new UniqueEnforcer();

const pushUnique = (item: number) => {
try {
arrayContainsUniqueItems.push(
uniqueEnforcer.enforce(item)
)
} catch (error) {
if (error instanceof EnforceUniqueError) {
return 'Item already exists';
}
}
};

pushUnique(1);

// logs 'Item already exists'
console.log(pushUnique(1));
`

Or you can provide a function that returns a value. enforce method will run this function until limits are exceeded
and will return the generated value. If limits are exceeded it will throw an EnforceLimitError.

`ts
const uniqueEnforcerEmail = new UniqueEnforcer();

function createRandomUser() {
const firstName = faker.person.firstName();
const lastName = faker.person.lastName();
const email = uniqueEnforcerEmail.enforce(() => {
return faker.internet.email({firstName, lastName});
});

return {
firstName,
lastName,
email,
};
}

// You can be sure that each user in the list has unique email
const users = []

for (let i = 0; i < 100; i++) {
users.push(createRandomUser())
}
`

$3

`ts
{
maxTime: 50,
maxRetries: 50,
}
`

Options

You can provide options object to change the defaults

`ts
const email = uniqueEnforcerEmail.enforce(
() => {
return faker.internet.email({firstName, lastName})
},
{
maxTime: 1000,
maxRetries: 1000,
exclude: [1]
},
);
`

$3

The time in milliseconds this method may take before throwing an EnforceLimitError

$3

The total number of attempts to try before throwing an EnforceLimitError

$3

Exclude specific value(s) from being returned.

Resetting

You can reset the unique enforcer instance to start over, clearing any previously stored values.

`ts
const uniqueEnforcer = new UniqueEnforcer();

const value1 = uniqueEnforcer.enforce('value');

uniqueEnforcer.reset();

// There will be no error thrown because of reset.
const value2 = uniqueEnforcer.enforce('value');
``