A deep extend implementation for underscore, lodash and their (AFAIK non-existent) friends.
Based conceptually on the _.extend() function in underscore.js.
Copyright (C) 2012 Kurt Milam - http://xioup.com
Licensed under the GPL V3+.
Original source: https://gist.github.com/1868955
npm install underscore-deep-extend
One of
- underscore.js
- lodash.js
- another clone that provides
_.each
and_.is(Array|Date|Null|Object|String|Undefined)
.
Load it, either as is (in the browser), as an AMD module, or as a CommonJS/Node.js module), then mix it in with the parent library (which must be explicitly injected):
_.mixin({deepExtend: underscoreDeepExtend(_)});
Call it like this:
var myObj = _.deepExtend(grandparent, child, grandchild, greatgrandchild)
This function is especially useful if you're working with JSON config documents. It allows you to create a default config document with the most common settings, then override those settings for specific cases. It accepts any number of objects as arguments, giving you fine-grained control over your config document hierarchy.
-
parentRE allows you to concatenate strings. example:
var obj = _.deepExtend({url: "www.example.com"}, {url: "http://#{_}/path/to/file.html"}); console.log(obj.url);
output:
http://www.example.com/path/to/file.html
-
parentRE also acts as a placeholder, which can be useful when you need to change one value in an array, while leaving the others untouched. example:
var arr = _.deepExtend([100, {id: 1234}, true, "foo", [250, 500]], ["#{_}", "#{_}", false, "#{_}", "#{_}"]); console.log(arr);
output:
[100, {id: 1234}, false, "foo", [250, 500]]
-
The previous example can also be written like this:
var arr = _.deepExtend([100, {id:1234}, true, "foo", [250, 500]], ["#{_}", {}, false, "#{_}", []]); console.log(arr);
output:
[100, {id: 1234}, false, "foo", [250, 500]]
-
And also like this:
var arr = _.deepExtend([100, {id:1234}, true, "foo", [250, 500]], ["#{_}", {}, false]); console.log(arr);
output:
[100, {id: 1234}, false, "foo", [250, 500]]
-
Array order is important. example:
var arr = _.deepExtend([1, 2, 3, 4], [1, 4, 3, 2]); console.log(arr);
output:
[1, 4, 3, 2]
-
You can remove an array element set in a parent object by setting the same index value to null in a child object. Example:
var obj = _.deepExtend({arr: [1, 2, 3, 4]}, {arr: ["#{_}", null]}); console.log(obj.arr);
output:
[1, 3, 4]