fn-params-parser

Function arguments parse and verify compiliance with specification

If You want to perform some type checks on function arguments but not interested in TypeScript or Flow and not interested in micro optimization this small lib could be helpfull.

Instalation

npm install --save fn-params-parser

Usage

const parser = require('fn-params-parser');

function myCoolFunction() {
    const args = parser(arguments,  [
        { name: 'p1', type: 'string'                          },
        { name: 'p2', type: ['object', Array], default: []    },
        { name: 'p3', type: 'object',          optional: true },
        { name: 'p4', type: 'function'                        }
    ];

    // now arguments are clean and confirm with spec
    console.log(args.p1, args.p2, args.p3, args.p4);
}

Now You can invoke function with two methods:

• position parameters
• one object parameter with keys as param name from spec

Examples of function invocation:

    myCoolFunction('abc', [1,2,3], function() {});
    // output: abc [ 1, 2, 3 ] null function () {}

    myCoolFunction({ p1: 'abc', p4: function() {} });
    // output: abc [] null function () {}

    myCoolFunction('abc');
    // output: Error: No proper p4 parameter data type. Expected type is: function!

Types

Type could be any JavaScript valid type returning by typeof operator (should be given as string for eg.: 'string', 'number', 'object', ...) or any constructor function (should be given as literal for eg.: Array, Car, Account, ...) in this case param type is checked by instanceof operator.