Autocomplete grunt task if Gruntfile.js is present

.grunt_bash_completion

# Create function that will run when a certain phrase is typed in terminal
# and tab key is pressed twice
_grunt_complete()
{
    # fill local variable with a list of completions
    local COMPLETES=`grep -s 'grunt\.registerTask' Gruntfile.js | sed "s/\s*grunt.registerTask('\([^']*\)',.*$/\1/g"`

    # we put the completions into $COMPREPLY using compgen
    COMPREPLY=( $(compgen -W "$COMPLETES" -- ${COMP_WORDS[COMP_CWORD]}) )
    return 0
}

# get completions for command 'grunt' from function '_grunt_complete()'
complete -F _grunt_complete grunt