disparity

What is disparity?

The disparity npm package is a tool for generating and applying diffs between text files. It is useful for comparing two versions of a file and highlighting the differences between them.

What are disparity's main functionalities?

Generate Unified Diff

This feature allows you to generate a unified diff between two strings. The code sample demonstrates how to use disparity to compare two versions of a text and output the differences in a unified diff format.

const disparity = require('disparity');
const oldText = 'Hello World!';
const newText = 'Hello Brave New World!';
const diff = disparity.unified(oldText, newText);
console.log(diff);

Apply Diff

This feature allows you to apply a diff to a string to generate a new version of the text. The code sample shows how to apply a previously generated diff to an old version of a text to produce the new version.

const disparity = require('disparity');
const oldText = 'Hello World!';
const diff = '--- a
+++ b
@@ -1 +1 @@
-Hello World!
+Hello Brave New World!';
const newText = disparity.apply(oldText, diff);
console.log(newText);

Other packages similar to disparity

diff

The diff package is a popular library for comparing text differences in JavaScript. It provides similar functionality to disparity, such as generating diffs and applying them. However, diff offers more options for customizing the diff output and supports more diff formats, making it a more versatile choice for complex diffing needs.

jsdiff

jsdiff is another library for computing text differences in JavaScript. It is similar to disparity in that it can generate and apply diffs, but it also provides additional features like character-level diffs and the ability to format diffs in various styles. jsdiff is widely used and has a larger community, which can be beneficial for support and finding examples.

README

disparity

Colorized string diff ideal for text/code that spans through multiple lines.

This is basically just a wrapper around diff and ansi-styles + line numbers and omitting lines that don't have changes and/or that wouldn't help user identify the diff "context".

We also replace some invisible chars to make it easier to understand what really changed from one file to another:

• \r becomes <CR>
• \n becomes <LF>
• \t becomes <tab>

Created mainly to be used by esformatter and other tools that might need to display a nice looking diff of source files.

API

var disparity = require('disparity');

chars(oldStr, newStr[, opts]):String

Diffs two blocks of text, comparing character by character and returns a String with ansi color codes.

var diff = disparity.chars(file1, file2);
console.log(diff);

Will return an empty string if oldStr === newStr;

// default options
var opts = {
  // how many lines to display before/after a line that contains diffs
  context: 3,
  // file paths displayed just before the diff
  paths: [disparity.removed, disparity.added]
};

unified(oldStr, newStr[, opts]):String

Returns ansi colorized unified diff.

Will return an empty string if oldStr === newStr;

var diff = disparity.unified(file1, file2, {
  paths: ['test/file1.js', 'test/file2.js']
});
console.log(diff);

unifiedNoColor(oldStr, newStr[, opts]):String

Returns unified diff. Useful for terminals that doesn't support colors.

Will return an empty string if oldStr === newStr;

var diff = disparity.unifiedNoColor(file1, file2, {
  paths: ['test/file1.js', 'test/file2.js']
});
console.log(diff);

removed:String

String used on the diff headers to say that chars/lines was removed.

// default value
disparity.removed = 'removed';

added:String

String used on the diff headers to say that chars/lines was added.

// default value
disparity.added = 'added';

colors:Object

Object containing references to all the colors used by disparity.

If you want a different output than ansi (eg. HTML) you can replace the color values:

// wrap blocks into custom tags
disparity.colors = {
  // chars diff
  charsRemoved: { open: '<bggreen>', close: '</bggreen>' },
  charsAdded: { open: '<bgred>', close: '</bgred>' },

  // unified diff
  removed: { open: '<red>', close: '</red>' },
  added: { open: '<green>', close: '</green>' },
  header: { open: '<yellow>', close: '</yellow>' },
  section: { open: '<magenta>', close: '</magenta>' }
};

CLI

disparity also have a command line interface:

disparity [OPTIONS] <file_1> <file_2>

Options:
  -c, --chars           Output char diff (default mode).
  -u, --unified         Output unified diff.
  --unified-no-color    Don't output colors.
  -v, --version         Display current version.
  -h, --help            Display this help.

PS: cli can only compare 2 external files at the moment, no stdin support.

License

Released under the MIT license.

Changelog

v3.2.0 (2021/01/20)

• Add support to context opt in unified function