@leptonite/environment-parser

@leptonite/environment-parser
=============================

@leptonite/environment-parser helps getting and validating values from environment variables.

``typescript
// create an EnvironmentParser for the environment of this process
const envParser = new EnvironmentParser();

// create an EnvironmentParser for a custom environment
const customEnvParser = new EnvironmentParser({
SOME: 'value',
FOO: 'bar',
});


// get mandatory string value
// throws Error if VAR is not set
const mandatoryString = envParser.getString('VAR');

// get and validate mandatory string value
// throws Error if VAR is not set or does not match the given pattern
const validatedMandatoryString = envParser.getString('VAR', /^[a-zA-Z0-9]{10,20}$/u);

// get optional string value
// returns undefined if VAR is not set
const optionalString = envParser.getOptionalString('VAR');

// get and validate optional string value
// returns undefined if VAR is not set
// throws Error if VAR does not match the given pattern
const validatedOptionalString = envParser.getOptionalString('VAR', /^[a-zA-Z0-9]{10,20}$/u);


// get mandatory integer value
// throws Error if VAR is not set
const mandatoryInteger = envParser.getInteger('VAR');

// get and validate mandatory integer value
// throws Error if VAR is not set or does not meet the given requirements
const validatedMandatoryInteger = envParser.getInteger('VAR', { min: 1, max: 999 });

// get optional integer value
// returns undefined if VAR is not set
const optionalInteger = envParser.getOptionalInteger('VAR');

// get and validate optional integer value
// returns undefined if VAR is not set
// throws Error if VAR does not match the given pattern
const validatedOptionalInteger = envParser.getOptionalInteger('VAR', { min: 1, max: 999 });


// get mandatory string value and validate it against the given options
// throws Error if VAR is not set or does not match one of the given options
const mandatoryOption = envParser.getOneOf('VAR', ['option1', 'option2']);

// get optional string value and validate it against the given options
// returns undefined if VAR is not set
// throws Error if VAR does not match one of the given options
const optionalOption = envParser.getOptionalOneOf('VAR', ['option1', 'option2']);
`

The getOptionalString(), getOptionalInteger() and getOptionalOneOf() methods don’t support default values. Use envParser.getOptionalString('VAR') ?? 'default'` instead.