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$async IIFE generator

A Node.js IIFE generator for

An online version of the IIFE generator is available on

Documentation is available on


npm install

What is IIFE?

IIFE (Immediately-invoked Function Expressions) is a coding pattern for loading a script. An IIFE can be used in the browser safely.

The IIFE generator makes it easy to generate an IIFE with a selection of $async modules. The IIFE generator provides compression via Google Closure Compiler (GCC) with Advanced mode for the best performance in all browsers.

The IIFE generator can be executed as a CLI program from the command-line, as a Node.js module and as a browser script (see for an online version).



The provided iife-cli.js script can be used from the command-line. The NPM package contains a npm run iife script.


Display usage information and a list with available modules.

npm run iife -- --help


The following command shows how to create an IIFE with unary format, output to path/to/iife.js and with 3 modules that automatically load the required dependencies.

npm run iife --  --format unary --compress --output path/to/iife.js --modules css-loader,localstorage,timing

Short flags and a space separated module list are supported.

npm run iife --  -f unary -c -o path/to/iife.js -m "css-loader localstorage timing"

When omitting the --output flag the script is printed to the console, e.g. for > output.js.

Node.js module

// load Node.js module
const iife = require('');

// return script text for inlining
// uses memory-cache @link
iife.generate(['css-loader', 'timing'], {
   debug: true, // debug sources
   format: 'unary' // !function(){ ... }()
}).then(function(iife_script) {
   // iife_script contains the IIFE script text


// output to file
iife.generate(['css-loader', 'timing'], {
   compress: true, // Google Closure Compiler API compression
   format: 'wrap', // (function(){ ... })()
   output: 'path/to/iife.js',
   output_stats: true // return { modules:[], size:0, gzip_size:0 }
}).then(function(stats) {
   // iife.js written


The Node.js module can be used efficiently within a Node.js CMS. IIFE's are cached in memory using memory-cache.

Warning: the generator depends on the free Google Closure Compiler API that may not be 100% reliable. When using the generator in production it may be an option to use a local Google Closure Compiler service.


A Node.js IIFE generator for





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