jsondiffpatch

Delta Format ============ This page intends to be a reference for JSON format used to represent deltas (i.e. the output of ```jsondiffpatch.diff```). This format was created with a balance between readability and low footprint in mind. - when diffing 2 objects, the delta will reflect the same object structure (common part on both sides) - to represent changed parts, arrays and magic numbers are used to keep a low footprint (i.e. you won't see verbosity like ```"type": "added"```) - keep it pure JSON serializable A great way to understand this format is using the "Annotated JSON" option in the [Live Demo](http://benjamine.github.com/jsondiffpatch/demo/index.html), and try the different left/right examples, or edit left/right JSON to see the annotated delta update as your type. Here's a complete reference of this format. Added ----- a value was added, i.e. it was ```undefined``` and now has a value. ``` javascript delta = [ newValue ] ``` Modified ----- a value was replaced by another value ``` javascript delta = [ oldValue, newValue ] ``` Deleted ----- a value was deleted, i.e. it had a value and is now ```undefined``` ``` javascript delta = [ oldValue, 0, 0 ] ``` Object with inner changes ----- value is an object, and there are nested changes inside its properties ``` javascript delta = { property1: innerDelta1, property2: innerDelta2, property5: innerDelta5 } ``` > Note: only properties with inner deltas are included Here's an example combining what we have: ``` delta = { property1: [ newValue1 ], // obj[property1] = newValue1 property2: [ oldValue2, newValue2 ] // obj[property2] = newValue2 (and previous value was oldValue2) property5: [ oldValue5, 0, 0 ] // delete obj[property5] (and previous value was oldValue5) } ``` Array with inner changes ----- value is an array, and there are nested changes inside its items ``` javascript delta = { _t: 'a', index1: innerDelta1, index2: innerDelta2, index5: innerDelta5 } ``` > Note: only indices with inner deltas are included > Note: _t: 'a', indicates this applies to an array, when patching if a regular object (or a value type) is found, an error will be thrown ### Index Notation Indices on array deltas can be expressed in two ways: - number: refers to the index in the final (right) state of the array, this is used to indicate items inserted. - underscore + number: refers to the index in the original (left) state of the array, this is used to indicate items removed, or moved. ### Array Moves an item was moved to a different position in the same array ``` javascript delta = [ '', destinationIndex, 3] ``` > Note: '' represents the moved item value, suppresed by default > Note: 3 is the magical number that indicates "array move" Text Diffs ---------- If two strings are compared and they are different, you will see as you expect: ``` javascript delta = [ "some text", "some text modified" ] ``` But if both strings are long enough, [a text diffing algorithm](https://code.google.com/p/google-diff-match-patch/) will be used to efficiently detect changes in parts of the text. You can modify the minimum length with: ``` javascript var customDiffPatch = jsondiffpatch.create({ textDiff: { minLength: 60 // default value } }); ``` And the delta will look like this: ``` javascript delta = [ unidiff, 0, 2 ] ``` > Note: 2 is the magical number that indicates "text diff" > Note: unidiff is actually a character-based variation of Unidiff format that is explained [here](https://code.google.com/p/google-diff-match-patch/wiki/Unidiff)