func-params

Run-Time Function Parameter Name Determination

About

This is a tiny JavaScript function for determining the names of the parameters of a function under run-time. It can be used as the building block for Dependency Injection or Named-Parameter implementations. The underlying problem is that there is no official JavaScript API to determine the names of the parameters of a function under run-time, except the ECMAScript 2015 Function.prototype.toString(). This library determines the names of the function parameters by parsing the source code of Function.prototype.toString(). Its parsing is not 100%, but is able to handle even complex syntax scenarios.

Installation

$ npm install func-params

Usage

const funcParams = require("func-params")

/*  simple example  */
funcParams(function (a, b, c, d) {})
// --> [ "a", "b", "c", "d" ]

/*  complex example  */
funcParams(function (
    a /* x,y */ = /* x,y */ `foo\`baz${bar + ",)" + (42 / 7)}bar`,
    b = x(42, 7),
    c = { foo: { bar: x(42, 7), baz: [ 2 / 3 ] } },
    d = 42
) {})
// --> [ "a", "b", "c", "d" ]

License

Copyright (c) 2018-2021 Dr. Ralf S. Engelschall (http://engelschall.com/)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.