JarCastingcopy-props 
Copy properties between two objects deeply.
Install
To install from npm:
$ npm i copy-props --save
Load this module
For Node.js:
const copyProps = require('copy-props');
For Web browser:
<script src="copy-props.min.js"></script>
Usage
Copy src to dst simply (and return dst) :
var src = { a: 1, b: { b1: 'bbb' }, c: 'ccc' };
var dst = { a: 2, b: { b1: 'xxx', b2: 'yyy' } };
copyProps(src, dst);
// => { a: 1, b: { b1: 'bbb', b2: 'yyy' }, c: 'ccc' }
Copy src to dst with property mapping (and return dst) :
var src = { a: 1, b: { b1: 'bbb' }, c: 'ccc', d: 'ddd' };
var dst = { f: { a: 2, b1: 'xxx', b2: 'yyy' }, e: 'zzz' };
copyProps(src, dst, {
a: 'f.a',
'b.b1': 'f.b1',
'b.b2': 'f.b2',
'c': 'f.c',
});
// => { f: { a: 1, b1: 'bbb', b2: 'yyy', c: 'ccc' }, e: 'zzz' }
Copy src to dst with convert function (and return dst) :
var src = { a: 1, b: { b1: 'bbb' } };
var dst = { a: 0 };
copyProps(src, dst, function(srcInfo) {
if (srcInfo.keyChain === 'a') {
return srcInfo.value * 2;
}
if (srcInfo.keyChain === 'b.b1') {
return srcInfo.value.toUpperCase();
}
});
// => { a: 2, b: { b1: 'BBB' } }
Can use an array instead of a map as property mapping :
var src = { a: 1, b: { c: 'CCC' }, d: { e: 'EEE' } };
var dst = { a: 9, b: { c: 'xxx' }, d: { e: 'yyy' } };
var fromto = [ 'b.c', 'd.e' ];
copyProps(src, dst, fromto);
// => { a: 9, b: { c: 'CCC' }, d: { e: 'EEE' } }
Can copy reversively (from dst to src) by reverse flag (and return src):
var src = { a: 1, b: { b1: 'bbb' }, c: 'ccc' };
var dst = { a: 2, b: { b1: 'xxx', b2: 'yyy' } };
copyProps(src, dst, true);
// => { a: 2, b: { b1: 'xxx', b2: 'yyy' }, c: 'ccc' }
var src = { a: 1, b: { b1: 'bbb' }, c: 'ccc', d: 'ddd' };
var dst = { f: { a: 2, b1: 'xxx', b2: 'yyy' }, e: 'zzz' };
copyProps(src, dst, {
a: 'f.a',
'b.b2': 'f.b2',
'c': 'f.c',
}, true);
// => { a: 2, b: { b1: 'bbb', b2: 'yyy' }, c: 'ccc', d: 'ddd' }
If a value of source property is undefined (when not using converter), or a result of converter is undefined (when using converter), the value is not copied.
var src = { a: 'A', b: undefined, c: null, d: 1 };
var dst = { a: 'a', b: 'b', c: 'c' };
copyProps(src, dst, function(srcInfo) {
if (srcInfo.keyChain === 'd') {
return undefined;
} else {
return srcInfo.value;
}
});
// => { a: 'A', b: 'b', c: null }
You can operate the parent node object directly in converter.
var src = { a: 1, b: 2 };
var dst = {};
copyProps(src, dst, function(srcInfo, dstInfo) {
Object.defineProperty(dstInfo.parent, dstInfo.key, {
writable: false,
enumerable: true,
configurable: false,
value: srcInfo.value * 2
})
}); // => { a: 2, b: 4 }
dst // => { a: 2, b: 4 }
dst.a = 9
dst // -> { a: 2, b: 4 }
API
copyProps(src, dst [, fromto] [, converter] [, reverse]) => object
Copy properties of src to dst deeply. If fromto is given, it is able to copy between different properties. If converter is given, it is able to convert the terminal values.
Parameters:
| Parameter | Type | Description |
|---|---|---|
| src | object | A source object of copy. |
| dst | object | A destinate object of copy. |
| fromto | object | array | An object mapping properties between src and dst. (Optional) |
| converter | function | A function to convert terminal values in src. (Optional) |
| reverse | boolean | True, if copying reversively from dst to src and returns src object. fromto is also reversively used from value to key. This default value is false. (Optional) |
Returns:
dst object after copying.
Type: object
-
Format of fromto
fromto is a non-nested key-value object. And the keys are property key chains of src and the values are property key chains of dst. The key chain is a string which is concatenated property keys on each level with dots, like
'aaa.bbb.ccc'.The following example copys the value of
src.aaa.bbb.ccctodst.xxx.yyy.copyProps(src, dst, { 'aaa.bbb.ccc' : 'xxx.yyy' })
fromto can be an array. In that case, the array works as a map which has pairs of same key and value.
-
API of converter
converter(srcInfo, dstInfo) : Any
converter is a function to convert terminal values of propeerties of src.
Parameters:
Parameter Type Description srcInfo object An object which has informations about the current node of src. dstInfo object An object which has informations about the current node of dst. Return:
The converted value to be set as a destination property value. If this value is undefined, the destination property is not set to the destination node object.
Type: Any
-
Properties of srcInfo and dstInfo
srcInfo and dstInfo has same properties, as follows:
Property Type Description value Any The value of the current node. key string The key name of the current node. keyChain string The full key of the current node concatenated with dot. depth number The depth of the current node. parent object The parent node of the current node.
-
License
Copyright (C) 2016-2021 Gulp Team.
This program is free software under MIT License. See the file LICENSE in this distribution for more details.
