fjl-error-throwing

fjl-error-throwing

Error throwing helpers. In particular for when a type doesn't match an expected type (or one of one or more expected types).

Stars of the show:

errorIfNotType and errorIfNotTypes (and their variants ( uncurried versions (same function names though with trailing '$' character))).

Docs

See inline 'readme' docs below or go to the jsdocs page: https://functional-jslib.github.io/fjl-error-throwing/

Install

npm install fjl-error-throwing

Methods

Note: For un-curried versions of the methods below access them with a trailing '$' character; Example errorIfNotType$(...) etc..

Note: For more extensive docs see jsdocs located at './jsdocs' (in the repo (currently))

errorIfNotType<Type, contextName, valueName, value, messageSuffix=null> {Undefined} -

Curried.  Throws an error when your `value` doesn't match given `type`.

errorIfNotTypes<Types, contextName, valueName, value> : {Undefined} -

Curried.  Throws an error when your `value` doesn't match one of the given `types` passed in.

getErrorIfNotTypeThrower<messageTmplFunction, typeChecker = defaultTypeChecker> : errorIfNotType - Gives an errorIfNotType

function (curried version) that uses the passed message template function to generate the error message string.

getErrorIfNotTypesThrower<messageTmplFunction, typeChecker = defaultTypeChecker> : errorIfNotTypes - Gives an errorIfNotTypes

function (curried version) that uses the passed message template function to generate the error message string.

Docs

More extensive docs can be found in './jsdocs' folder. Docs will go up somewhere later. @todo

Types:

TemplateContext     {Object<value, valueName, expectedTypeName, foundTypeName, messageSuffix>}
Type                {String|Function} - Constructor name or constructor itself.
TypesArray          {Array<Type>}
TypeChecker         {Function<Type, Any>}
ErrorMessageCall    {Function<TemplateContext>}
ErrorIfNotType      {Function<Type, contextName, valueName, value>:Undefined}
ErrorIfNotTypes     {Function<TypesArray, contextName, valueName, value>:Undefined}

Usage

@todo add more extensive usage examples

import {
    getErrorIfNotTypeThrower, // For passing your own error string renderer
    getErrorIfNotTypesThrower, // For passing your own error string renderer
    errorIfNotType,
    errorIfNotTypes
} from 'fjl-errorThrowing';

const errorIfNotFunction = errorIfNotType(Function); // curried so makes for useful usage
    
function someFunc (fn) {
    errorIfNotFunction('someFunc', 'fn', fn); // Will throw well detailed error when `value` is not a function
    // Do something here ...
}

someFunc(_ => 1 + 1);  // No error here
someFunc(99);   // Error here type doesn't match expected type.

Development

1. npm install
2. Look at node scripts in package.json.

Testing

1. npm test (after npm install).

License

GNU v2, v3