Compiling CoffeeScript with Vim

Published: 2011-10-20

You can configure Vim to automatically compile CoffeeScript files when you save them from within Vim, it’s easy, just add an autocmd to run the CoffeeScript compiler to your ~/.vimrc file:

autocmd BufWritePost,FileWritePost *.coffee :silent !coffee -c <afile>

I prefer this to the CoffeeScript compiler --watch option because you get to see any compiler errors in the editor when you save the CoffeeScript source file.

Tip	Use Ctrl+L to clear any compiler errors and redraw the screen.

This technique works, but what happens if you want to selectively include CoffeeScript compiler options with some files and not others? I came up against this problem writing QUnit tests using CoffeeScript which must be compiled without the top-level function wrapper using the --bare command-line option.

My solution was to take a cue from Vim’s mode line feature and write a CoffeeScript compiler wrapper shell script which scans the end of the CoffeeScript source file for a comment line starting with # coffee:, it then passes the remainder of the line to the CoffeeScript compiler as command-line options. Here’s a basic CoffeeScript QUnit test file specifying the --bare option in the trailing mode line:

module 'Test' test 'addition', -> equals 1+1, 2, 'one and one is two' # coffee: --bare

And here’s the coffee.sh wrapper script:

#!/bin/sh # # 'Mode line' wrapper for CoffeeScript 'coffee' compiler command. # # Executes CoffeeScript compiler and includes compiler options from line at the # end of the CoffeeScript source file starting with '# coffee:' (c.f. Vim mode # lines). # # Last argument is the source file name. for srcfile; do true; done # Search the last 5 lines in the source for a mode line and extract the # trailing coffee command options. pat='^#\s*coffee:' opts=`tail -n5 $srcfile | grep "$pat" | sed "/$pat/s/$pat//"` coffee $opts $@

You also need to change coffee to coffee.sh in your ~/.vimrc autocmd plus you need to ensure both coffee to coffee.sh are in your shell search PATH:

autocmd BufWritePost,FileWritePost *.coffee :silent !coffee.sh -c <afile>

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