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harmonica v1.2.2

A module that allows use of Node.js --harmony flags, programmatically.

harmonica Build Status

A module that allows use of Node.js --harmony flags, programmatically.


Harmonica allows developers to use --harmony flags programmatically. That means an end to specifying command-line options for experimental "harmony" features of Node.js/V8. If you've ever wanted to use experimental features within Gulp tasks, or have a need to run an app through wrappers like forever, this module takes the command-line headache out of the equation.


Node Version Requirements

Harmonica should work with Node.js version 4.6.2 and higher. However, specifying flags which don't exist for a particular version will likely result in an error.


Install the module:

npm install harmonica

Initialize the module. By default, harmonica will use the --harmony flag, which will enable all harmony, in-progress features.


Specifying Flags

Should you need only specific flags, pass an Array of strings representing the flags you want to enable, without the leading hyphens, as the first parameter.


Syntax Flags

Some flags, such as --harmony-async-await, enable syntax features in Node.js. Should you require flags meant to extend the syntax, you must create an entry point in a separate file from which to initialize harmonica. You can then require the main script for your app, which contains the body of code.

Please see the tests for an example which uses the async / await syntax.

Listing Available Flags

If you have the need to view all available harmony flags for your version of node, you may do so by executing the following in a terminal:

node --v8-options | grep "in progress"


default([flags], [options])


Type: Array
Default: undefined

See Specifying Flags


Type: Object
Default: { silent: false }

Example Usage of all options:

require('harmonica')({ silent: true });

Or, if you need to specify flags:

  { silent: true });

Type: Boolean
Default: false

Should you wish to silence harmonica's output, set a silent property on options to false.


dcodeIO wrote and published the wonderful harmonize module. Harmonica is a complete rewrite of harmonize, but follows the same principles.

@stuk was kind enough to allow me to use the 'harmonica' module name in the NPM registry.

Harmonica vector base by saicreative.


MIT © Andrew Powell


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