#mitto

mitto is a small library that helps package creators search the file directory of the application consuming their package for its relevant config.

Package creators can even drop a .mitto file into their root folder and specify required and optional parameters with type-checking (including descriptive error messages for package consumers if a required parameter is not present or is of the wrong type).

Reasons to use mitto:

• Quick and painless to start writing your package with a user-provided config in mind
• required or optional parameter enforcement with type-checking for your configs
• Descriptive error messages for the user when something is misconfigured
• .mitto gives your package consumers a common area to see what configurations are available and/or expected

Installation

npm install mitto --save

Usage

Using mitto as a simple file/config finder without a .mitto file

    var mitto = require('mitto');

    var myConfig = mitto.loadConfig('config_i_need.json');

    if (myConfig) {
        //DO STUFF
    } else {
        //YELL AT USER AND CONFIGURE THINGS MYSELF
    }

Using mitto for type-checked configuration expression with a .mitto file

Create a .mitto config file in your root folder:

{
    "name" : "name_of_the_config_file_you_expect_the_user_to_provide.json",
    "required" : {
        "areWeHavingFun" : {
            "type" : "boolean",   //valid types: "undefined", "object", "boolean", "number", "string", "symbol", "function"
            "description" : "boolean that represents if we're having fun" // **Optional**, you don't have to include "description"
        },
        "maximumBeerCount" : {
            "type" : "number"
        } 
    },
    "optional" : {
        "partyResponsibly" : {
            "type" : "boolean",
            "description" : "boolean indicating if we should party responsibly",
            "default" : false // **Optional**, the default value if the user doesn't provide a value or doesn't have a configuration at all
        }
    }
}

The code we write will be exactly the same, except anything we get from the user will be compared with your .mitto and type-checked:

    var mitto = require('mitto');

    var myConfig = mitto.loadConfig('config_i_need.json');

    if (myConfig) {
        //DO STUFF
    } else {
        //CONFIGURE THINGS MYSELF
    }

Error Handling

.mitto has required attributes?	User has a configuration file?	Error handling behavior
Yes	Yes	Only throws errors if user is missing a required parameter or has a parameter of an invalid type.
Yes	No	Throws an error that the configuration is missing.
No	Yes	Does not throw errors. loadConfig() will return NULL or an object with defaults.
No	No	Does not throw errors. loadConfig() will return NULL or an object with defaults.

Tests

npm test

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code.

Release History

• 0.3.0 Unified API under loadConfig. mitto now "requires" the object for you. .mitto is now more explicit and detailed.
• 0.2.0 Switch from object-templating to .mitto templating, separate opinionated call from non-opiniated.
• 0.1.0 Initial release

License

MIT License