jsfu

Improve your Javascript fu with language extensions

jsfu is a dead simple rewriter, without any grammars, AST:s or parsers.
All extensions will be pluggable and it will be easy include your own.

The current version (0.1.2) contains two extensions.
An interface for modifying which extensions get loaded is not yet available.

This code is currently experimental.

Install

npm install jsfu

Or globally

npm install -g jsfu

Usage

From the command line

Transpile files from src/jsfu to bin/js

$ jsfu --input src/jsfu --output bin/js

Run the included example with

$ jsfu example sushi

Add the -p parameter to see the transpiled source of the example,
or store it in a file with `--output ``

Read from stdin to stdout using

-s or --stdin for stdin
-p or --print for stdout

$ echo '(a, b) => {}' | jsfu -sp | grep function
function(a, b) {}

From node.js

var jsfu = require('jsfu');
var source = '(a, b) => {};';
var transpiled = jsfu(source); 
console.log(transpiled);

will output

function(a, b) {};

Extensions

Automatic Continuation of Async calls

The Automatic Continuation feature replaces the § symbol
with a callback containing any code that appears below the function call.

It will turn

var piece = buy('sushi', §, '$100');
eat(piece);

into

buy('sushi', function(piece) { 
	eat(piece);
}, '$100');

Another example, before transcompilation:

function getSushi(piece, callback) {
	// Lunch hour. Need to stand in line first.
	setTimeout(function() { callback(piece); }, 5000);
}

var sushi = getSushi('tamago', §);
console.log(sushi + ' was good');

After transcompilation:

function getSushi(piece, callback) {
	// Lunch hour. Need to stand in line first.
	setTimeout(function() { callback(piece); }, 5000);
}

getSushi('tamago', function(sushi) {
	console.log(sushi + ' was good');
});

Async Wrapping

Parallel calls are supported by encapsulating the code inside a function:

Without async wrapping:

var r = A($);
var r = C($);
var r = B($);

This will first run A
When A is completed C will run
When C is completed B will run

With async wrapping:

function runAC() {
	var a = A($);
    var c = C($); 
}
runAC();
var b = B($);

This will run A and B in parallel
When A is completed C will run

Compact function definitions

Use an arrow to create compact function definitions Useful when passing a function as a parameter

Turns

// A parameter
buy('sushi', (err, piece) => { eat(piece) });

// Or a definition
var onGotSushi = (err, piece) => { eat(piece) };

into

// A parameter
buy('sushi', function(err, piece) { eat(piece) });

// Or a definition	
onGotSushi = function(err, piece) { eat(piece) };

Known Bugs

A bracket } symbol below an asynchronous call that's not part of its wrapping function will cause an error.

Example

	function wrappingFunction() {
		var sushi = getSushi(§);
		sushi.eatSelf();
		myRating = { rating: 5 } // <- this } will cause an error
	} // <- this } will not cause an error

This bug will be fixed in 0.1.3

License

(The MIT License)

Copyright (c) 2012 Charlie Rudenstål <charlie4@gmail.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.