var-diff

get the difference between two variables

$3

| IE | Chrome | Firefox | Opera | Safari |
| :-: | :-: | :-: | :-: | :--: |
| ✔️ | ✔️ | ✔️ | ✔️ | ✔️ |

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``bash
npm i var-diff
`
or
`html

`

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use var patches = diff.get(origin, target, [key]) to get difference patches between origin and target variables.

key is an optional parameter used to improve sorting performance.
patches is an array containing all of the differences betwen two variables

`
// patches
t: type 1-create 2-delete 3-edit 4-replace
p: path {Array}
v: value
i: new index(when type is replace)
`

use diff.apply(origin, patches) to make the origin variable apply the patches then become the target varible. but all references of the origin variable are reserved.

`javascript
const diff = require('var-diff');

let a = [1, 2, 3, {id: 1, name: 'tom'}, {id: 2, name: 'jack'}]
let b = [2, {id: 2, name: 'will'}, 3, {id: 1, name: 'lucy'}]

let patches = diff.get(origin, target, 'id');
console.log(patches);

/**
* patches
[
{ t: 2, p: [ 0 ] }, // remove the 0th element
{ t: 3, p: [ 2, 'name' ], v: 'lucy' }, // update the name of the 2th element to 'lucy'
{ t: 3, p: [ 3, 'name' ], v: 'will' }, // update the name of the 3th element to 'will'
{ t: 4, p: [ 3 ], i: 1 }, // change the 3th element to the 1th position
{ t: 4, p: [ 3 ], i: 2 } // change the 3th element to the 2th position
]
*/


a = diff.apply(a, patches);

console.log(JSON.stringify(a) === JSON.stringify(b));

// true
`

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`javascript
var a = {
name: 'tom',
gender: 'male',
list: [{
id: 1,
label: 'teacher'
}]
}

var b = {
name: 'jack',
list: [{
id: 2,
label: 'worker'
}, {
id: 3,
label: 'student'
}, {
id: 1,
label: ''
}]
}

p = diff.get(a, b, 'id');

console.log(p);
/**
t: type 1-create 2-delete 3-edit 4-replace
p: path {Array}
v: value
i: new index(when type is replace)

[{ t: 3, p: [ 'name' ], v: 'jack' },
{ t: 2, p: [ 'gender' ] },
{ t: 3, p: [ 'list', 0, 'label' ], v: '' },
{ t: 1, p: [ 'list', 1 ], v: { id: 2, label: 'worker' } },
{ t: 1, p: [ 'list', 2 ], v: { id: 3, label: 'student' } },
{ t: 4, p: [ 'list', 0 ], i: 2 },
{ t: 4, p: [ 'list', 1 ], i: 0 },
{ t: 1, p: [ 'age' ], v: 25 }]
*/

var aa = diff.apply(a, p, 'id'); // key
console.log(JSON.stringify(aa) === JSON.stringify(b)); // true
`


`javascript
var a = [NaN, NaN];
var b = [NaN, NaN];

var p = diff.get(a, b, 'id');

console.log(p); // []
``

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MIT