jsdiff
A javascript text differencing implementation.
Based on the algorithm proposed in "An O(ND) Difference Algorithm and its Variations" (Myers, 1986).
Installation
npm install diff --save
API
-
Diff.diffChars(oldStr, newStr[, options])- diffs two blocks of text, comparing character by character.Returns a list of change objects (See below).
Options
ignoreCase:trueto ignore casing difference. Defaults tofalse.
-
Diff.diffWords(oldStr, newStr[, options])- diffs two blocks of text, comparing word by word, ignoring whitespace.Returns a list of change objects (See below).
Options
ignoreCase: Same as indiffChars.
-
Diff.diffWordsWithSpace(oldStr, newStr[, options])- diffs two blocks of text, comparing word by word, treating whitespace as significant.Returns a list of change objects (See below).
-
Diff.diffLines(oldStr, newStr[, options])- diffs two blocks of text, comparing line by line.Options
ignoreWhitespace:trueto ignore leading and trailing whitespace. This is the same asdiffTrimmedLinesnewlineIsToken:trueto treat newline characters as separate tokens. This allows for changes to the newline structure to occur independently of the line content and to be treated as such. In general this is the more human friendly form ofdiffLinesanddiffLinesis better suited for patches and other computer friendly output.
Returns a list of change objects (See below).
-
Diff.diffTrimmedLines(oldStr, newStr[, options])- diffs two blocks of text, comparing line by line, ignoring leading and trailing whitespace.Returns a list of change objects (See below).
-
Diff.diffSentences(oldStr, newStr[, options])- diffs two blocks of text, comparing sentence by sentence.Returns a list of change objects (See below).
-
Diff.diffCss(oldStr, newStr[, options])- diffs two blocks of text, comparing CSS tokens.Returns a list of change objects (See below).
-
Diff.diffJson(oldObj, newObj[, options])- diffs two JSON objects, comparing the fields defined on each. The order of fields, etc does not matter in this comparison.Returns a list of change objects (See below).
-
Diff.diffArrays(oldArr, newArr[, options])- diffs two arrays, comparing each item for strict equality (===).Options
comparator:function(left, right)for custom equality checks
Returns a list of change objects (See below).
-
Diff.createTwoFilesPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader)- creates a unified diff patch.Parameters:
oldFileName: String to be output in the filename section of the patch for the removalsnewFileName: String to be output in the filename section of the patch for the additionsoldStr: Original string valuenewStr: New string valueoldHeader: Additional information to include in the old file headernewHeader: Additional information to include in the new file headeroptions: An object with options. Currently, onlycontextis supported and describes how many lines of context should be included.
-
Diff.createPatch(fileName, oldStr, newStr, oldHeader, newHeader)- creates a unified diff patch.Just like Diff.createTwoFilesPatch, but with oldFileName being equal to newFileName.
-
Diff.structuredPatch(oldFileName, newFileName, oldStr, newStr, oldHeader, newHeader, options)- returns an object with an array of hunk objects.This method is similar to createTwoFilesPatch, but returns a data structure suitable for further processing. Parameters are the same as createTwoFilesPatch. The data structure returned may look like this:
{ oldFileName: 'oldfile', newFileName: 'newfile', oldHeader: 'header1', newHeader: 'header2', hunks: [{ oldStart: 1, oldLines: 3, newStart: 1, newLines: 3, lines: [' line2', ' line3', '-line4', '+line5', '\\ No newline at end of file'], }] }
-
Diff.applyPatch(source, patch[, options])- applies a unified diff patch.Return a string containing new version of provided data.
patchmay be a string diff or the output from theparsePatchorstructuredPatchmethods.The optional
optionsobject may have the following keys:fuzzFactor: Number of lines that are allowed to differ before rejecting a patch. Defaults to 0.compareLine(lineNumber, line, operation, patchContent): Callback used to compare to given lines to determine if they should be considered equal when patching. Defaults to strict equality but may be overridden to provide fuzzier comparison. Should return false if the lines should be rejected.
-
Diff.applyPatches(patch, options)- applies one or more patches.This method will iterate over the contents of the patch and apply to data provided through callbacks. The general flow for each patch index is:
options.loadFile(index, callback)is called. The caller should then load the contents of the file and then pass that to thecallback(err, data)callback. Passing anerrwill terminate further patch execution.options.patched(index, content, callback)is called once the patch has been applied.contentwill be the return value fromapplyPatch. When it's ready, the caller should callcallback(err)callback. Passing anerrwill terminate further patch execution.
Once all patches have been applied or an error occurs, the
options.complete(err)callback is made. -
Diff.parsePatch(diffStr)- Parses a patch into structured dataReturn a JSON object representation of the a patch, suitable for use with the
applyPatchmethod. This parses to the same structure returned byDiff.structuredPatch. -
convertChangesToXML(changes)- converts a list of changes to a serialized XML format
All methods above which accept the optional callback method will run in sync mode when that parameter is omitted and in async mode when supplied. This allows for larger diffs without blocking the event loop. This may be passed either directly as the final parameter or as the callback field in the options object.
Change Objects
Many of the methods above return change objects. These objects consist of the following fields:
value: Text contentadded: True if the value was inserted into the new stringremoved: True if the value was removed from the old string
Note that some cases may omit a particular flag field. Comparison on the flag fields should always be done in a truthy or falsy manner.
Examples
Basic example in Node
require('colors');
const Diff = require('diff');
const one = 'beep boop';
const other = 'beep boob blah';
const diff = Diff.diffChars(one, other);
diff.forEach((part) => {
// green for additions, red for deletions
// grey for common parts
const color = part.added ? 'green' :
part.removed ? 'red' : 'grey';
process.stderr.write(part.value[color]);
});
console.log();
Running the above program should yield
Basic example in a web page
<pre id="display"></pre>
<script src="diff.js"></script>
<script>
const one = 'beep boop',
other = 'beep boob blah',
color = '';
let span = null;
const diff = Diff.diffChars(one, other),
display = document.getElementById('display'),
fragment = document.createDocumentFragment();
diff.forEach((part) => {
// green for additions, red for deletions
// grey for common parts
const color = part.added ? 'green' :
part.removed ? 'red' : 'grey';
span = document.createElement('span');
span.style.color = color;
span.appendChild(document
.createTextNode(part.value));
fragment.appendChild(span);
});
display.appendChild(fragment);
</script>
Open the above .html file in a browser and you should see
Compatibility
jsdiff supports all ES3 environments with some known issues on IE8 and below. Under these browsers some diff algorithms such as word diff and others may fail due to lack of support for capturing groups in the split operation.
License
See LICENSE.
![[Regression] Bad merge when adding new files](https://avatars.githubusercontent.com/u/532414?v=4)
![[question] Is it possible to preserve the whitespace when using `ignoreWhitespace` ? It breaks the formatting](https://avatars.githubusercontent.com/u/275001?v=4)
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