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A javascript text differencing implementation.

Based on the algorithm proposed in"An O(ND) Difference Algorithm and its Variations" (Myers, 1986).

npm install diff

or

bower install jsdiff

• JsDiff.diffChars(oldStr, newStr[, options]) - diffs two blocks of text, comparing character by character.

  Returns a list of change objects (See below).

• JsDiff.diffWords(oldStr, newStr[, options]) - diffs two blocks of text, comparing word by word, ignoring whitespace.

  Returns a list of change objects (See below).

• JsDiff.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).

• JsDiff.diffLines(oldStr, newStr[, options]) - diffs two blocks of text, comparing line by line.

  Options*ignoreWhitespace:true to ignore leading and trailing whitespace. This is the same asdiffTrimmedLines*newlineIsToken:true to 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 ofdiffLines anddiffLines is better suited for patches and other computer friendly output.

  Returns a list of change objects (See below).

• JsDiff.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).

• JsDiff.diffSentences(oldStr, newStr[, options]) - diffs two blocks of text, comparing sentence by sentence.

  Returns a list of change objects (See below).

• JsDiff.diffCss(oldStr, newStr[, options]) - diffs two blocks of text, comparing CSS tokens.

  Returns a list of change objects (See below).

• JsDiff.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).

• JsDiff.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 removals
  • newFileName : String to be output in the filename section of the patch for the additions
  • oldStr : Original string value
  • newStr : New string value
  • oldHeader : Additional information to include in the old file header
  • newHeader : Additional information to include in the new file header
  • options : An object with options. Currently, onlycontext is supported and describes how many lines of context should be included.

• JsDiff.createPatch(fileName, oldStr, newStr, oldHeader, newHeader) - creates a unified diff patch.

  Just like JsDiff.createTwoFilesPatch, but with oldFileName being equal to newFileName.

• JsDiff.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 structuresuitable 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'],}]}

• JsDiff.applyPatch(source, patch[, options]) - applies a unified diff patch.

  Return a string containing new version of provided data.patch may be a string diff or the output from theparsePatch orstructuredPatch methods.

  The optionaloptions object 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 overriden to provide fuzzier comparison. Should return false if the lines should be rejected.

• JsDiff.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 anerr will terminate further patch execution.
  • options.patched(index, content) is called once the patch has been applied.content will be the return value fromapplyPatch.

  Once all patches have been applied or an error occurs, theoptions.complete(err) callback is made.

• JsDiff.parsePatch(diffStr) - Parses a patch into structured data

  Return a JSON object representation of the a patch, suitable for use with theapplyPatch method. This parses to the same structure returned byJsDiff.structuredPatch.

• convertChangesToXML(changes) - converts a list of changes to a serialized XML format

All methods above which accept the optionalcallback 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 thecallback field in theoptions object.

Many of the methods above return change objects. These objects consist of the following fields:

• value: Text content
• added: True if the value was inserted into the new string
• removed: True of 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.

Basic example in Node

require('colors')varjsdiff=require('diff');varone='beep boop';varother='beep boob blah';vardiff=jsdiff.diffChars(one,other);diff.forEach(function(part){// green for additions, red for deletions// grey for common partsvarcolor=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

<preid="display"></pre><scriptsrc="diff.js"></script><script>varone='beep boop';varother='beep boob blah';vardiff=JsDiff.diffChars(one,other);vardisplay=document.getElementById('display');diff.forEach(function(part){// green for additions, red for deletions// grey for common partsvarcolor=part.added ?'green' :part.removed ?'red' :'grey';varspan=document.createElement('span');span.style.color=color;span.appendChild(document.createTextNode(part.value));display.appendChild(span);});</script>

Open the above .html file in a browser and you should see

Full online demo

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 thesplit operation.

SeeLICENSE.