diff-upsert

DiffUpsert deep diffs a modified Javascript object with a base object using recursive matcher.
DiffUpsert can also upsert a delta into a base object to bring it up-to-date.
This is helpful for managing changes to JSON configurations with deep trees.

NOTE: Contrast this behavior with the standard Object.assign() method, which only handles shallow deltas.

#### Base Object
``
var jbase = {
color: 'red',
sleeve: {
length: 31,
},
}
`

#### Updated Object
`
var jupdated = {
color: 'red',
sleeve: {
length: 32, // updated property
},
}
`

#### diff
`
var du = new DiffUpsert();
var delta = du.diff(jupdated, jbase);
//{
// sleeve: {
// length: 32, // updated property
// },
//}
`

#### upsert
`
// jbase.sleeve.length === 31
du.upsert(jbase, delta);
// jbase.sleeve.length === 32
`

#### excludeKeys
DiffUpsert can be configured to ignore selected keys:
`
var du = new DiffUpsert({
excludeKeys: /^\$.*/,
});
``