updated docs...

Signed-off-by: Alex A. Naanou <alex.nanou@gmail.com>
This commit is contained in:
Alex A. Naanou 2018-09-25 04:29:10 +03:00
parent 612b42ff9c
commit 3e6c83d4a9

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*Object diff* is a not-so-basic diff/patch/pattern/compare implementation for JavaScript objects / object trees.
For a walkthrough by example see the [introduction](#introduction), for the general docs start at [motivation](#motivation) section or look through the index below.
- [Object diff](#object-diff)
- [Introduction](#introduction)
- [Seeing the difference (*diff*)](#seeing-the-difference-diff)
@ -10,7 +12,7 @@
- [Checking](#checking)
- [Generic ways to compare objects (*patterns*)](#generic-ways-to-compare-objects-patterns)
- [Motivation](#motivation)
- [Goals / Features](#goals--features)
- [Features](#features)
- [Installation and loading](#installation-and-loading)
- [Diff](#diff)
- [Diff class API](#diff-class-api)
@ -71,13 +73,16 @@ var Diff = require('object-diff').Diff
var diff = Diff(Bill, Ted)
```
Here's how different `Bill` and `Ted` really are (this is how the *diff* looks like):
Here's how different `Bill` and `Ted` really are (the *diff* format):
```javascript
// log out the relevant part...
//JSON.stringify(diff.diff, null, '\t')
[
// each element of the array is a change...
{
// the path tells us how to reach the change location...
"path": ["name"],
// A and B are the states before/after the change...
"A": "Bill",
"B": "Ted"
},
@ -87,11 +92,14 @@ Here's how different `Bill` and `Ted` really are (this is how the *diff* looks l
"B": "blond"
},
{
// note this path, we'll explain it a bit later...
"path": ["skills", [[2, 0], [2, 1]]],
// also note that either A or B can be omited...
"B": [
"guitar"
]
},
// this change might look redundant but it is not...
{
"path": ["skills", "length"],
"A": 2,
@ -108,7 +116,7 @@ This tells us that we have four *differences* or *changes*:
Some words on the format:
- `A` and `B` indicate the states of the *change* in the input objects,
- `path` tells us how to reach the *change* in the inputs,
- The odd thing in `"path"` of the third change is the *index* of the change in the input `"skills"` arrays where each element (`[2, 0]` and `[2, 1]`) describes the spot in the array that changed in the corresponding input object. Each element consists of two items, the first is the actual *index* or position of the change (in both cases `2`) and the second is the length of the change (`0` and `1` respectively, meaning that in `A` we have zero or no items and in `B` one),
- The array in `"path"` of the third change is the *index* of the change in the input `"skills"` arrays where each element (`[2, 0]` and `[2, 1]`) describes the spot in the array that changed in the corresponding input object. Each element consists of two items, the first is the actual *index* or position of the change (in both cases `2`) and the second is the length of the change (`0` and `1` respectively, meaning that in `A` we have zero or no items and in `B` one),
- `"A"` or `"B"` may not be present in the change (change #3) if the change describes simple item addition or removal,
- The format is redundant in places by design, for example here you can both infer `"skills"` *length* from the *changes* applied to it and we have an explicit `["path", "length"]` *change*. This is mainly to support cases where inferring array length from changes to it may not be possible, like for sparse arrays.
@ -223,9 +231,10 @@ cmp(Bill, BILL_or_TED_L) // -> true
## Motivation
Originally this module was designed/written as a way to locate and store only the changed parts of rather big JSON objects/trees, but the specific use cases (*[ImageGrid](https://github.com/flynx/ImageGrid) and [pWiki](https://github.com/flynx/pWiki)*) required additional features not provided by the available at the time alternative implementations (listing in next section).
Originally this module was designed/written as a way to locate and store only the changed parts of rather big JSON objects/trees.
The specific use cases (*[ImageGrid](https://github.com/flynx/ImageGrid) and [pWiki](https://github.com/flynx/pWiki)*) required additional features not provided by the available at the time alternative implementations (listing in next section).
### Goals / Features
### Features
- JSON *diff* support
- JavaScript object support including objects/types not supported in JSON
- ~~Optional attribute order support~~ (not done yet)
@ -233,8 +242,6 @@ Originally this module was designed/written as a way to locate and store only th
- *Text diff* (multi-line strings) support
- Object patterns as a means to simplify structural comparison/testing
- Configurable and extensible implementation
- As simple as possible
- *Fun*
XXX alternatives
@ -349,7 +356,7 @@ Additionally attribute changes are supported for all non basic objects (i.e. any
### Extended 'Text' object support
A *text* is JavaScript string that is long (>1000 chars, configurable in [Oprions](#options)) and multiline string.
A *text* is JavaScript string that is long (>100 chars, configurable in [Oprions](#options)) and/or a multiline string.
A *text* is treated as an `Array` containing the string split into lines (split by `'\n'`).