validate-params

A small parameter validation library

The purpose of this library is to easily check that the contract of your functions are not violated; and if they are, to allow you to gracefully handle the situation (provide useful error messages).

Basic examples

var Validator = require('validate-params');

// validating a single argument
function simpleWrapper(callback){
    Validator.assert.arg(callback, 'function');
    //Then do something with the callback later
    //At this point we can be sure that callback is a function
}

simpleWrapper(42); //throws Error('Expected type "function" but it was type "number"')

// validating an argument object
function myCoolFunction(opts){
    Validator.assert.arg(opts,
    {name: 'string',
    //handles optional parameters
     phoneNum: {
        type: 'string',
        optional: true
     },
     //handles nested objects
     location: {
        city: 'string',
        longitude: 'number',
        latitude: 'number'
     }
    });
    //...
}

myCoolFunction({name: 'Jenny',
                phoneNum: '876-5309',
                location: {
                   city: 'Chicago',
                   longitude: 87.6847,
                   latitude: 41.8369
                }
               });

//There is also a less invasive variant of the validator
function maybeCallback(callback){
    var isCallbackAFunction = Validator.validate.arg(callback, 'function');
    if(isCallbackAFunction){
        //do some cool callback stuff
    }
}

maybeCallback(5); //No error is thrown

Installation

npm install --save-dev validate-params

Documentation

To learn more checkout the documentation page