unidiff

unidiff adds support for creating unified diff format to jsdiff

The following snippet:

var unidiff = require('unidiff')

var diff = unidiff.diffLines(
    'a quick\nbrown\nfox\njumped\nover\nthe\nlazy\ndog\n',
    'a quick\nbrown\ncat\njumped\nat\nthe\nnot-so-lazy\nfox\n'
)
console.log(unidiff.formatLines(diff), {context: 2})

Produces this unified diff output:

--- a
+++ b
@@ -1,8 +1,8 @@
 a quick
 brown
-fox
+cat
 jumped
-over
+at
 the
-lazy
-dog
+not-so-lazy
+fox

This same output can be achieved more concisely using the diffAsText function:

console.log(require('unidiff').diffAsText(
    'a quick\nbrown\nfox\njumped\nover\nthe\nlazy\ndog\n',
    'a quick\nbrown\ncat\njumped\nat\nthe\nnot-so-lazy\nfox\n'
))

Both formatLines() and diffAsText() take a format options parameter with the following options.

{
    aname:        file name for input a, defaults to 'a'
    bname:        file name for input b, defaults to 'b'
    pre_context:  write up to this many unmodified lines before each change
    post_context: write up to this many unmodified lines after each change
    context:      default values for pre_context and post_context (specify both in one setting)
                  (context defaults to 3 when nothing is specified)
    format:       format of output text.  currently only "unified" is supported
}

Differences From JSDiff

All js-diff functions are also availalbe in unidiff, with a couple minor changes:

• unidiff.diffLines() and unidiff.diffAsText() accept arrays of strings as well as strings with new lines for input.
• unidiff.diffLines() returns an empty array when there are no differences instead of an array with a single unmodified change.

Useful features to add to unidiff

• implement parsing of unified format to convert text output into patches.