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    assert-options
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    0.7.0 • Public • Published

    assert-options

    Smart options handling, with one line of code:

    • throw detailed error on invalid options
    • set default values for missing options

    Strongly-typed, built with TypeScript 4.x strict mode, for JavaScript clients.

    Build Status Coverage Status

    Rationale

    • Passing in invalid or misspelled option names is one of the most common errors in JavaScript.
    • Assigning defaults is the most common operation for methods that take options.

    This module automates proper options handling - parsing and setting defaults where needed.

    Although this library is implemented in TypeScript, its objective is mainly to help JavaScript clients, because TypeScript itself can handle invalid options and defaults natively.

    Installation

    $ npm i assert-options
    

    Usage

    const { assertOptions } = require('assert-options');
    
    function functionWithOptions(options) {
        options = assertOptions(options, {first: 123, second: null});
        
        // options is a safe object here, with all missing defaults set.
    }

    When default values are not needed, you can just use an array of strings:

    function functionWithOptions(options) {
        options = assertOptions(options, ['first', 'second']);
        
        // the result is exactly the same as using the following:
        // options = assertOptions(options, {first: undefined, second: undefined});
        
        // options is a safe object here, without defaults.
    }

    API

    assertOptions(options, defaults) => {}

    • When options is null/undefined, new {} is returned, applying defaults as specified.

    • When options contains an unknown property, Error Option "name" is not recognized. is thrown.

    • When a property in options is missing or undefined, its value is set from the defaults, provided it is available and its value is not undefined.

    • When options is not null/undefined, it must be of type object, or else TypeError is thrown: Invalid "options" parameter: value.

    • Parameter defaults is required, as a non-null object or an array of strings, or else TypeError is thrown: Invalid "defaults" parameter: value.

    Install

    npm i assert-options

    DownloadsWeekly Downloads

    172,818

    Version

    0.7.0

    License

    MIT

    Unpacked Size

    6.73 kB

    Total Files

    5

    Last publish

    Collaborators

    • vitaly.tomilov