feat: add symbol/to-string-tag

lib/node_modules/@stdlib/symbol/to-string-tag/README.md

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+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2025 The Stdlib Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+-->
+
+# ToStringTagSymbol
+
+> To string tag [symbol][mdn-symbol-tostringtag] which is used to customize the string description of an object.
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- Package usage documentation. -->
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var ToStringTagSymbol = require( '@stdlib/symbol/to-string-tag' );
+```
+
+#### ToStringTagSymbol
+
+To string tag [`symbol`][mdn-symbol-tostringtag] which is used to customize the string description of an object.
+
+```javascript
+var s = typeof ToStringTagSymbol;
+// e.g., returns 'symbol'
+```
+
+</section>
+
+<!-- /.usage -->
+
+<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+## Notes
+
+-   The [symbol][mdn-symbol] is only supported in environments which support [symbols][mdn-symbol]. In non-supporting environments, the value is `null`.
+-   The `Object.prototype.toString` method uses the `Symbol.toStringTag` property, if present, as the tag in the string representation. For example, an object with `obj[Symbol.toStringTag] = 'Custom'` will return `'[object Custom]'` when `Object.prototype.toString.call(obj)` is invoked.
+
+</section>
+
+<!-- /.notes -->
+
+<!-- Package usage examples. -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var ToStringTagSymbol = require( '@stdlib/symbol/to-string-tag' );
+
+function valueOfCustom() {
+    return 'custom';
+}
+
+var obj = {};
+obj.valueOf = valueOfCustom;
+
+obj[ ToStringTagSymbol ] = 'Custom';
+
+console.log( Object.prototype.toString.call( obj ) );
+// => '[object Custom]'
+
+var arr = [];
+console.log( Object.prototype.toString.call( arr ) );
+// => '[object Array]'
+
+arr[ ToStringTagSymbol ] = 'MyArray';
+console.log( Object.prototype.toString.call( arr ) );
+// => '[object MyArray]'
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="references">
+
+</section>
+
+<!-- /.references -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+[mdn-symbol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol
+[mdn-symbol-tostringtag]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/toStringTag
+
+</section>
+
+<!-- /.links -->

lib/node_modules/@stdlib/symbol/to-string-tag/docs/repl.txt

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+
+{{alias}}
+    To string tag.
+
+    This symbol is used to determine whether a constructor object recognizes an
+    object as its instance.
+
+    The symbol is only supported in ES6/ES2015+ environments. For non-supporting
+    environments, the value is `null`.
+
+    Examples
+    --------
+    > var s = {{alias}}
+    e.g., <symbol>
+
+    See Also
+    --------
+

lib/node_modules/@stdlib/symbol/to-string-tag/docs/types/index.d.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+// TypeScript Version: 4.1
+
+// EXPORTS //
+
+/**
+* Has instance symbol.
+*
+* ## Notes
+*
+* -   This symbol is used to determine whether a constructor object recognizes an object as its instance.
+* -   The symbol is only supported in ES6/ES2015+ environments. For non-supporting environments, the value is `null`.
+*/
+export = Symbol.toStringTag;

lib/node_modules/@stdlib/symbol/to-string-tag/docs/types/test.ts

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+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+/* eslint-disable @typescript-eslint/no-unused-expressions */
+
+import ToStringTag = require( './index' );
+
+
+// TESTS //
+
+// The exported value is the `toStringTag` symbol...
+{
+	ToStringTag;
+}

lib/node_modules/@stdlib/symbol/to-string-tag/examples/index.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+var isArray = require( '@stdlib/assert/is-array' );
+var instanceOf = require( '@stdlib/assert/instance-of' );
+var defineProperty = require( '@stdlib/utils/define-property' );
+var ToStringTagSymbol = require( './../lib' );
+
+function ArrayLike() {
+	return {
+		'length': 3,
+		'0': 4,
+		'1': 5,
+		'2': 6
+	};
+}
+
+function toStringTag( instance ) {
+	return isArray( instance );
+}
+
+var x = [ 1, 2, 3 ];
+
+defineProperty( ArrayLike, ToStringTagSymbol, {
+	'configurable': true,
+	'value': null
+});
+console.log( instanceOf( x, ArrayLike ) );
+
+defineProperty( ArrayLike, ToStringTagSymbol, {
+	'configurable': true,
+	'value': toStringTag
+});
+console.log( instanceOf( x, ArrayLike ) );

lib/node_modules/@stdlib/symbol/to-string-tag/lib/index.js

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+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+/**
+* Symbol used to determine if a constructor object recognizes an object as its instance.
+*
+* @module @stdlib/symbol/to-string-tag
+*
+* @example
+* var isArray = require( '@stdlib/assert/is-array' );
+* var ToStringTagSymbol = require( '@stdlib/symbol/to-string-tag' );
+*
+* function ArrayLike() {
+*     return {
+*         'length': 3,
+*         '0': 1,
+*         '1': 2,
+*         '2': 3
+*     };
+* };
+*
+* ArrayLike[ ToStringTagSymbol ] = isArray;
+*/
+
+// MAIN //
+
+var main = require( './main.js' );
+
+
+// EXPORTS //
+
+module.exports = main;

lib/node_modules/@stdlib/symbol/to-string-tag/lib/main.js

@@ -0,0 +1,54 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2025 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var hasToStringTagSymbolSupport = require( '@stdlib/assert/has-tostringtag-support' ); // eslint-disable-line id-length
+
+
+// MAIN //
+
+/**
+* Has instance symbol.
+*
+* @name ToStringTagSymbol
+* @constant
+* @type {(symbol|null)}
+*
+* @example
+* var isArray = require( '@stdlib/assert/is-array' );
+*
+* function ArrayLike() {
+*     return {
+*         'length': 3,
+*         '0': 1,
+*         '1': 2,
+*         '2': 3
+*     };
+* };
+*
+* ArrayLike[ ToStringTagSymbol ] = isArray;
+*/
+var ToStringTagSymbol = ( hasToStringTagSymbolSupport() ) ? Symbol.toStringTag : null; // eslint-disable-line max-len
+
+
+// EXPORTS //
+
+module.exports = ToStringTagSymbol;