120 lines
2.6 KiB
Markdown
120 lines
2.6 KiB
Markdown
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@license Apache-2.0
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Copyright (c) 2018 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# writableProperties
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> Return an array of an object's own writable property names and symbols.
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<section class="usage">
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## Usage
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```javascript
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var writableProperties = require( '@stdlib/utils/writable-properties' );
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```
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#### writableProperties( obj )
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Returns an `array` of an object's own writable property names and symbols.
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```javascript
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var obj = {
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'a': 1,
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'b': 2
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};
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var props = writableProperties( obj );
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// e.g., returns [ 'a', 'b' ]
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```
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</section>
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<!-- /.usage -->
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<section class="notes">
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## Notes
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- Property order is not guaranteed, as `object` property enumeration is not specified according to the [ECMAScript specification][ecma-262-for-in]. In practice, however, most engines use insertion order to sort an `object`'s properties, thus allowing for deterministic extraction.
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</section>
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<!-- /.notes -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var defineProperty = require( '@stdlib/utils/define-property' );
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var hasSymbolSupport = require( '@stdlib/assert/has-symbol-support' );
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var Symbol = require( '@stdlib/symbol/ctor' );
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var writableProperties = require( '@stdlib/utils/writable-properties' );
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var hasSymbols = hasSymbolSupport();
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var props;
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var obj;
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function Foo() {
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this.a = 'a';
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defineProperty( this, 'b', {
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'configurable': true,
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'enumerable': true,
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'writable': false,
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'value': 'b'
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});
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if ( hasSymbols ) {
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this[ Symbol( 'a' ) ] = 'a';
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defineProperty( this, Symbol( 'b' ), {
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'configurable': true,
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'enumerable': true,
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'writable': false,
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'value': 'b'
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});
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}
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return this;
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}
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Foo.prototype.c = 'c';
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if ( hasSymbols ) {
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Foo.prototype[ Symbol( 'c' ) ] = 'c';
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}
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obj = new Foo();
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props = writableProperties( obj );
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console.log( props );
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// e.g., => [ 'a', ... ]
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```
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</section>
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<!-- /.examples -->
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<section class="links">
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[ecma-262-for-in]: http://www.ecma-international.org/ecma-262/5.1/#sec-12.6.4
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</section>
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<!-- /.links -->
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