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diff --git a/files/it/web/javascript/data_structures/index.html b/files/it/web/javascript/data_structures/index.html new file mode 100644 index 0000000000..a056282b0d --- /dev/null +++ b/files/it/web/javascript/data_structures/index.html @@ -0,0 +1,444 @@ +--- +title: Tipi di dato e strutture in JavaScript +slug: Web/JavaScript/Data_structures +tags: + - Guide + - JavaScript + - Principianti + - tipi +translation_of: Web/JavaScript/Data_structures +--- +<div>{{jsSidebar("More")}}</div> + +<p>Tutti i linguaggi di programmazione utilizzano strutture di dati, ma queste possono spesso differire da un linguaggio all'altro. L'intento di questo articolo è elencare tutte le strutture di dati di JavaScript e le relative proprietà, che possono essere utilizzate anche per costruire nuove strutture di dati. Dove possible, compareremo le strutture di dati di JavaScript con quelle di altri linguaggi.</p> + +<h2 id="Tipi_dinamici">Tipi dinamici</h2> + +<p>JavaScript è un linguaggio di <em>tipo debole</em> o <em>dinamico</em>. Questo vuol dire che in JavaScript le variabili non sono direttamente associate a nessun particolare tipo e che una variabile può essere assegnata (e ri-assegnata) a qualsiasi tipo di valore:</p> + +<pre class="brush: js">let foo = 42; // foo è ora Number +foo = 'bar'; // foo è ora String +foo = true; // foo è ora Boolean +</pre> + +<h2 id="Tipi_di_dati">Tipi di dati</h2> + +<p>L'ultima definizione dello standard ECMAScript comprende nove tipi:</p> + +<ul> + <li>Sei tipi di dati sono <a href="/it/docs/Glossary/Primitive">primitivi</a>: + + <ul> + <li><a href="/it/docs/Glossary/undefined">undefined</a> : <code>typeof instance === "undefined"</code></li> + <li><a href="/en-US/docs/Glossary/Boolean">Boolean</a> : <code>typeof instance === "boolean"</code></li> + <li><a href="/en-US/docs/Glossary/Number">Number</a> : <code>typeof instance === "number"</code></li> + <li><a href="/en-US/docs/Glossary/String">String</a> : <code>typeof instance === "string"</code></li> + <li><a href="/en-US/docs/Glossary/BigInt">BigInt</a><span> : </span><code>typeof instance === "bigint"</code></li> + <li><a href="/en-US/docs/Glossary/Symbol">Symbol</a><span> : </span><code>typeof instance === "symbol"</code></li> + </ul> + </li> + <li><a href="/en-US/docs/Glossary/Null">null</a><span> : </span><code>typeof instance === "object"</code>. È uno speciale tipo <a href="https://wiki.developer.mozilla.org/it/docs/Glossary/Primitive">primitivo</a> che ha un uso aggiuntivo per il suo valore: se l'oggetto non è ereditato, viene mostrato <code>null</code>;</li> + <li><a href="/en-US/docs/Glossary/Object">Object</a><span> : </span><code>typeof instance === "object"</code>. Non è un tipo di dato ma bensì un tipo strutturale per ogni istanza di oggetto <a href="https://wiki.developer.mozilla.org/it/docs/Learn/JavaScript/Oggetti">costruito</a> utilizzata anche come struttura di dati: new <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object">Object</a>, new <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array">Array</a>, new <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map">Map</a>, new <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set">Set</a>, new <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap">WeakMap</a>, new <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet">WeakSet</a>, new <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date">Date</a> e praticamente tutto creato con la <a href="https://wiki.developer.mozilla.org/it/docs/Web/JavaScript/Reference/Operators/new">parola chiave new</a>;</li> + <li><a href="/en-US/docs/Glossary/Function">Function</a><span> non data structure, though it also answers for typeof operator: </span><code>typeof instance === "function"</code>. This answer is done as a special shorthand for Functions, though every Function constructor is derived from Object constructor.</li> +</ul> + +<p>Keep in mind the only valuable purpose of <code>typeof</code> operator usage is checking the Data Type. If we wish to check any Structural Type derived from Object it is pointless to use <code>typeof</code> for that, as we will always receive <code>"object"</code>. The indeed proper way to check what sort of Object we are using an <a href="/en-US/docs/Web/JavaScript/Reference/Operators/instanceof">instanceof</a> keyword. But even in that case there might be misconceptions.</p> + +<h2 id="Valori_primitivi">Valori primitivi</h2> + +<p>All types except objects define immutable values (that is, values which can't be changed). For example (and unlike in C), Strings are immutable. We refer to values of these types as "<em>primitive values</em>".</p> + +<h3 id="Tipo_Boolean">Tipo Boolean</h3> + +<p>Boolean represents a logical entity and can have two values: <code>true</code> and <code>false</code>. See <a href="/en-US/docs/Glossary/Boolean">Boolean</a> and {{jsxref("Boolean")}} for more details.</p> + +<h3 id="Tipo_Null">Tipo Null</h3> + +<p>The Null type has exactly one value: <code>null</code>. See {{jsxref("null")}} and <a href="/en-US/docs/Glossary/Null">Null</a> for more details.</p> + +<h3 id="Tipo_Undefined">Tipo Undefined</h3> + +<p>A variable that has not been assigned a value has the value <code>undefined</code>. See {{jsxref("undefined")}} and <a href="/en-US/docs/Glossary/Undefined">Undefined</a> for more details.</p> + +<h3 id="Tipo_Number">Tipo Number</h3> + +<p>ECMAScript has two built-in numeric types: <strong>Number</strong> and <strong>BigInt</strong> (see below).</p> + +<p>The Number type is a <a href="http://en.wikipedia.org/wiki/Double_precision_floating-point_format">double-precision 64-bit binary format IEEE 754 value</a> (numbers between -(2<sup>53</sup> − 1) and 2<sup>53</sup> − 1). In addition to representing floating-point numbers, the number type has three symbolic values: <code>+Infinity</code>, <code>-Infinity</code>, and {{jsxref("NaN")}} ("<strong>N</strong>ot a <strong>N</strong>umber").</p> + +<p>To check for the largest available value or smallest available value within {{jsxref("Infinity", "±Infinity")}}, you can use the constants {{jsxref("Number.MAX_VALUE")}} or {{jsxref("Number.MIN_VALUE")}}.</p> + +<p>Starting with ECMAScript 2015, you are also able to check if a number is in the double-precision floating-point number range using {{jsxref("Number.isSafeInteger()")}} as well as {{jsxref("Number.MAX_SAFE_INTEGER")}} and {{jsxref("Number.MIN_SAFE_INTEGER")}}. Beyond this range, integers in JavaScript are not safe anymore and will be a double-precision floating point approximation of the value.</p> + +<p>The number type has only one integer with two representations: <code>0</code> is represented as both <code>-0</code> and <code>+0</code>. (<code>0</code> is an alias for <code>+0</code>.) </p> + +<p>In the praxis, this has almost no impact. For example, <code>+0 === -0</code> is <code>true</code>. However, you are able to notice this when you divide by zero:</p> + +<pre class="brush: js">> 42 / +0 +Infinity +> 42 / -0 +-Infinity +</pre> + +<p>Although a number often represents only its value, JavaScript provides {{jsxref("Operators/Bitwise_Operators", "binary (bitwise) operators")}}.</p> + +<p>These bitwise operators can be used to represent several Boolean values within a single number using <a class="external" href="http://en.wikipedia.org/wiki/Mask_%28computing%29">bit masking</a>. However, this is usually considered a bad practice, since JavaScript offers other means to represent a set of Booleans (like an array of Booleans, or an object with Boolean values assigned to named properties). Bit masking also tends to make the code more difficult to read, understand, and maintain.</p> + +<p>It may be necessary to use such techniques in very constrained environments, like when trying to cope with the limitations of local storage, or in extreme cases (such as when each bit over the network counts). This technique should only be considered when it is the last measure that can be taken to optimize size.</p> + +<h3 id="BigInt_type">BigInt type</h3> + +<p>The {{jsxref("BigInt")}} type is a numeric primitive in JavaScript that can represent integers with arbitrary precision. With <code>BigInt</code>s, you can safely store and operate on large integers even beyond the safe integer limit for <code>Number</code>s.</p> + +<p>A <code>BigInt</code> is created by appending <code>n</code> to the end of an integer or by calling the constructor.</p> + +<p>You can obtain the safest value that can be incremented with <code>Number</code>s by using the constant {{jsxref("Number.MAX_SAFE_INTEGER")}}. With the introduction of <code>BigInt</code>s, you can operate with numbers beyond the {{jsxref("Number.MAX_SAFE_INTEGER")}}.</p> + +<p>This example demonstrates, where incrementing the {{jsxref("Number.MAX_SAFE_INTEGER")}} returns the expected result:</p> + +<pre class="brush: js">> const x = 2n ** 53n; +9007199254740992n +> const y = x + 1n; +9007199254740993n +</pre> + +<p>You can use the operators <code>+</code>, <code>*</code>, <code>-</code>, <code>**</code>, and <code>%</code> with <code>BigInt</code>s—just like with <code>Number</code>s. A <code>BigInt</code> is not strictly equal to a <code>Number</code>, but it is loosely so.</p> + +<p>A <code>BigInt</code> behaves like a <code>Number</code> in cases where it is converted to <code>Boolean</code>: <code>if</code>, <code>||</code>, <code>&&</code>, <code>Boolean</code>, <code>!</code>.</p> + +<p><code>BigInt</code>s cannot be operated on interchangeably with <code>Number</code>s. Instead a {{jsxref("TypeError")}} will be thrown.</p> + +<h3 id="String_type">String type</h3> + +<p>JavaScript's {{jsxref("String")}} type is used to represent textual data. It is a set of "elements" of 16-bit unsigned integer values. Each element in the String occupies a position in the String. The first element is at index <code>0</code>, the next at index <code>1</code>, and so on. The length of a String is the number of elements in it.</p> + +<p>Unlike some programming languages (such as C), JavaScript strings are immutable. This means that once a string is created, it is not possible to modify it.</p> + +<p>However, it is still possible to create another string based on an operation on the original string. For example:</p> + +<ul> + <li>A substring of the original by picking individual letters or using {{jsxref("String.substr()")}}.</li> + <li>A concatenation of two strings using the concatenation operator (<code>+</code>) or {{jsxref("String.concat()")}}.</li> +</ul> + +<h4 id="Beware_of_stringly-typing_your_code!">Beware of "stringly-typing" your code!</h4> + +<p>It can be tempting to use strings to represent complex data. Doing this comes with short-term benefits:</p> + +<ul> + <li>It is easy to build complex strings with concatenation.</li> + <li>Strings are easy to debug (what you see printed is always what is in the string).</li> + <li>Strings are the common denominator of a lot of APIs (<a href="/en-US/docs/Web/API/HTMLInputElement" title="HTMLInputElement">input fields</a>, <a href="/en-US/docs/Storage" title="Storage">local storage</a> values, <a href="/en-US/docs/Web/API/XMLHttpRequest" title="Use XMLHttpRequest (XHR) objects to interact with servers. You can retrieve data from a URL without having to do a full page refresh. This enables a Web page to update just part of a page without disrupting what the user is doing."><code>XMLHttpRequest</code></a> responses when using <code>responseText</code>, etc.) and it can be tempting to only work with strings.</li> +</ul> + +<p>With conventions, it is possible to represent any data structure in a string. This does not make it a good idea. For instance, with a separator, one could emulate a list (while a JavaScript array would be more suitable). Unfortunately, when the separator is used in one of the "list" elements, then, the list is broken. An escape character can be chosen, etc. All of this requires conventions and creates an unnecessary maintenance burden.</p> + +<p>Use strings for textual data. When representing complex data, parse strings and use the appropriate abstraction.</p> + +<h3 id="Symbol_type">Symbol type</h3> + +<p>Symbols are new to JavaScript in ECMAScript 2015. A Symbol is a <strong>unique</strong> and <strong>immutable</strong> primitive value and may be used as the key of an Object property (see below). In some programming languages, Symbols are called "atoms".</p> + +<p>For more details see <a href="/en-US/docs/Glossary/Symbol">Symbol</a> and the {{jsxref("Symbol")}} object wrapper in JavaScript.</p> + +<h2 id="Oggetti">Oggetti</h2> + +<p>In computer science, an object is a value in memory which is possibly referenced by an <a href="/en-US/docs/Glossary/Identifier">identifier</a>.</p> + +<h3 id="Proprietà">Proprietà</h3> + +<p>In JavaScript, objects can be seen as a collection of properties. With the <a href="/en-US/docs/Web/JavaScript/Guide/Values,_variables,_and_literals#Object_literals">object literal syntax</a>, a limited set of properties are initialized; then properties can be added and removed. Property values can be values of any type, including other objects, which enables building complex data structures. Properties are identified using <em>key</em> values. A <em>key</em> value is either a String or a Symbol value.</p> + +<p>There are two types of object properties which have certain attributes: The <em>data</em> property and the <em>accessor</em> property.</p> + +<h4 id="Data_property">Data property</h4> + +<p>Associates a key with a value, and has the following attributes:</p> + +<table class="standard-table"> + <caption>Attributes of a data property</caption> + <thead> + <tr> + <th scope="col">Attributo</th> + <th scope="col">Tipo</th> + <th scope="col">Descrizione</th> + <th scope="col">Valore di default</th> + </tr> + </thead> + <tbody> + <tr> + <td>[[Value]]</td> + <td>Any JavaScript type</td> + <td>The value retrieved by a get access of the property.</td> + <td><code>undefined</code></td> + </tr> + <tr> + <td>[[Writable]]</td> + <td>Boolean</td> + <td>If <code>false</code>, the property's [[Value]] cannot be changed.</td> + <td><code>false</code></td> + </tr> + <tr> + <td>[[Enumerable]]</td> + <td>Boolean</td> + <td> + <p>If <code>true</code>, the property will be enumerated in <a href="/en-US/docs/Web/JavaScript/Reference/Statements/for...in">for...in</a> loops.<br> + See also <a href="/en-US/docs/Web/JavaScript/Enumerability_and_ownership_of_properties">Enumerability and ownership of properties</a>.</p> + </td> + <td><code>false</code></td> + </tr> + <tr> + <td>[[Configurable]]</td> + <td>Boolean</td> + <td>If <code>false</code>, the property cannot be deleted, cannot be changed to an accessor property, and attributes other than [[Value]] and [[Writable]] cannot be changed.</td> + <td><code>false</code></td> + </tr> + </tbody> +</table> + +<table class="standard-table"> + <caption>Obsolete attributes (as of ECMAScript 3, renamed in ECMAScript 5)</caption> + <thead> + <tr> + <th scope="col">Attributo</th> + <th scope="col">Tipo</th> + <th scope="col">Descrizione</th> + </tr> + </thead> + <tbody> + <tr> + <td>Read-only</td> + <td>Boolean</td> + <td>Reversed state of the ES5 [[Writable]] attribute.</td> + </tr> + <tr> + <td>DontEnum</td> + <td>Boolean</td> + <td>Reversed state of the ES5 [[Enumerable]] attribute.</td> + </tr> + <tr> + <td>DontDelete</td> + <td>Boolean</td> + <td>Reversed state of the ES5 [[Configurable]] attribute.</td> + </tr> + </tbody> +</table> + +<h4 id="Accessor_property">Accessor property</h4> + +<p>Associates a key with one of two accessor functions (<code>get</code> and <code>set</code>) to retrieve or store a value, and has the following attributes:</p> + +<table class="standard-table"> + <caption>Attributes of an accessor property</caption> + <thead> + <tr> + <th scope="col">Attribute</th> + <th scope="col">Type</th> + <th scope="col">Description</th> + <th scope="col">Default value</th> + </tr> + </thead> + <tbody> + <tr> + <td>[[Get]]</td> + <td>Function object or <code>undefined</code></td> + <td>The function is called with an empty argument list and retrieves the property value whenever a get access to the value is performed.<br> + See also <a href="/en-US/docs/Web/JavaScript/Reference/Operators/get"><code>get</code></a>.</td> + <td><code>undefined</code></td> + </tr> + <tr> + <td>[[Set]]</td> + <td>Function object or <code>undefined</code></td> + <td>The function is called with an argument that contains the assigned value and is executed whenever a specified property is attempted to be changed.<br> + See also <a href="/en-US/docs/Web/JavaScript/Reference/Operators/set"><code>set</code></a>.</td> + <td><code>undefined</code></td> + </tr> + <tr> + <td>[[Enumerable]]</td> + <td>Boolean</td> + <td>If <code>true</code>, the property will be enumerated in <a href="/en-US/docs/Web/JavaScript/Reference/Statements/for...in">for...in</a> loops.</td> + <td><code>false</code></td> + </tr> + <tr> + <td>[[Configurable]]</td> + <td>Boolean</td> + <td>If <code>false</code>, the property can't be deleted and can't be changed to a data property.</td> + <td><code>false</code></td> + </tr> + </tbody> +</table> + +<div class="note"> +<p><strong>Note: </strong>Attribute is usually used by JavaScript engine, so you can't directly access it (see more about {{jsxref("Object.defineProperty()")}}). That's why the attribute is put in double square brackets instead of single.</p> +</div> + +<h3 id="Normal_objects_and_functions">"Normal" objects, and functions</h3> + +<p>A JavaScript object is a mapping between <em>keys</em> and <em>values</em>. Keys are strings (or {{jsxref("Symbol")}}s), and <em>values</em> can be anything. This makes objects a natural fit for <a class="external" href="http://en.wikipedia.org/wiki/Hash_table">hashmaps</a>.</p> + +<p>Functions are regular objects with the additional capability of being <em>callable</em>.</p> + +<h3 id="Dates">Dates</h3> + +<p>When representing dates, the best choice is to use the built-in <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date"><code>Date</code> utility</a> in JavaScript.</p> + +<h3 id="Indexed_collections_Arrays_and_typed_Arrays">Indexed collections: Arrays and typed Arrays</h3> + +<p><a href="/en-US/docs/JavaScript/Reference/Global_Objects/Array" title="Array">Arrays</a> are regular objects for which there is a particular relationship between integer-key-ed properties and the <code>length</code> property.</p> + +<p>Additionally, arrays inherit from <code>Array.prototype</code>, which provides to them a handful of convenient methods to manipulate arrays. For example, <code><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf" title="en/JavaScript/Reference/Global_Objects/Array/indexOf">indexOf</a></code> (searching a value in the array) or <code><a href="/en-US/docs/JavaScript/Reference/Global_Objects/Array/push" title="en/JavaScript/Reference/Global_Objects/Array/push">push</a></code> (adding an element to the array), and so on. This makes Arrays a perfect candidate to represent lists or sets.</p> + +<p><a href="/en-US/docs/Web/JavaScript/Typed_arrays">Typed Arrays</a> are new to JavaScript with ECMAScript 2015, and present an array-like view of an underlying binary data buffer. The following table helps determine the equivalent C data types:</p> + +<table class="standard-table"> + <thead> + <tr> + <th class="header" scope="col">Type</th> + <th class="header" scope="col">Value Range</th> + <th class="header" scope="col">Size in bytes</th> + <th class="header" scope="col">Description</th> + <th class="header" scope="col">Web IDL type</th> + <th class="header" scope="col">Equivalent C type</th> + </tr> + </thead> + <tbody> + <tr> + <td>{{jsxref("Int8Array")}}</td> + <td><code>-128</code> to <code>127</code></td> + <td>1</td> + <td>8-bit two's complement signed integer</td> + <td><code>byte</code></td> + <td><code>int8_t</code></td> + </tr> + <tr> + <td>{{jsxref("Uint8Array")}}</td> + <td><code>0</code> to <code>255</code></td> + <td>1</td> + <td>8-bit unsigned integer</td> + <td><code>octet</code></td> + <td><code>uint8_t</code></td> + </tr> + <tr> + <td>{{jsxref("Uint8ClampedArray")}}</td> + <td><code>0</code> to <code>255</code></td> + <td>1</td> + <td>8-bit unsigned integer (clamped)</td> + <td><code>octet</code></td> + <td><code>uint8_t</code></td> + </tr> + <tr> + <td>{{jsxref("Int16Array")}}</td> + <td><code>-32768</code> to <code>32767</code></td> + <td>2</td> + <td>16-bit two's complement signed integer</td> + <td><code>short</code></td> + <td><code>int16_t</code></td> + </tr> + <tr> + <td>{{jsxref("Uint16Array")}}</td> + <td><code>0</code> to <code>65535</code></td> + <td>2</td> + <td>16-bit unsigned integer</td> + <td><code>unsigned short</code></td> + <td><code>uint16_t</code></td> + </tr> + <tr> + <td>{{jsxref("Int32Array")}}</td> + <td><code>-2147483648</code> to <code>2147483647</code></td> + <td>4</td> + <td>32-bit two's complement signed integer</td> + <td><code>long</code></td> + <td><code>int32_t</code></td> + </tr> + <tr> + <td>{{jsxref("Uint32Array")}}</td> + <td><code>0</code> to <code>4294967295</code></td> + <td>4</td> + <td>32-bit unsigned integer</td> + <td><code>unsigned long</code></td> + <td><code>uint32_t</code></td> + </tr> + <tr> + <td>{{jsxref("Float32Array")}}</td> + <td><code>1.2</code><span>×</span><code>10<sup>-38</sup></code> to <code>3.4</code><span>×</span><code>10<sup>38</sup></code></td> + <td>4</td> + <td>32-bit IEEE floating point number (7 significant digits e.g., <code>1.1234567</code>)</td> + <td><code>unrestricted float</code></td> + <td><code>float</code></td> + </tr> + <tr> + <td>{{jsxref("Float64Array")}}</td> + <td><code>5.0</code><span>×</span><code>10<sup>-324</sup></code> to <code>1.8</code><span>×</span><code>10<sup>308</sup></code></td> + <td>8</td> + <td>64-bit IEEE floating point number (16 significant digits e.g., <code>1.123...15</code>)</td> + <td><code>unrestricted double</code></td> + <td><code>double</code></td> + </tr> + <tr> + <td>{{jsxref("BigInt64Array")}}</td> + <td><code>-2<sup>63</sup></code> to <code>2<sup>63</sup>-1</code></td> + <td>8</td> + <td>64-bit two's complement signed integer</td> + <td><code>bigint</code></td> + <td><code>int64_t (signed long long)</code></td> + </tr> + <tr> + <td>{{jsxref("BigUint64Array")}}</td> + <td><code>0</code> to <code>2<sup>64</sup>-1</code></td> + <td>8</td> + <td>64-bit unsigned integer</td> + <td><code>bigint</code></td> + <td><code>uint64_t (unsigned long long)</code></td> + </tr> + </tbody> +</table> + +<h3 id="Keyed_collections_Maps_Sets_WeakMaps_WeakSets">Keyed collections: Maps, Sets, WeakMaps, WeakSets</h3> + +<p>These data structures, introduced in ECMAScript Edition 6, take object references as keys. {{jsxref("Set")}} and {{jsxref("WeakSet")}} represent a set of objects, while {{jsxref("Map")}} and {{jsxref("WeakMap")}} associate a value to an object.</p> + +<p>The difference between <code>Map</code>s and <code>WeakMap</code>s is that in the former, object keys can be enumerated over. This allows garbage collection optimizations in the latter case.</p> + +<p>One could implement <code>Map</code>s and <code>Set</code>s in pure ECMAScript 5. However, since objects cannot be compared (in the sense of <code><</code> "less than", for instance), look-up performance would necessarily be linear. Native implementations of them (including <code>WeakMap</code>s) can have look-up performance that is approximately logarithmic to constant time.</p> + +<p>Usually, to bind data to a DOM node, one could set properties directly on the object, or use <code>data-*</code> attributes. This has the downside that the data is available to any script running in the same context. <code>Map</code>s and <code>WeakMap</code>s make it easy to <em>privately</em> bind data to an object.</p> + +<h3 id="Structured_data_JSON">Structured data: JSON</h3> + +<p>JSON (<strong>J</strong>ava<strong>S</strong>cript <strong>O</strong>bject <strong>N</strong>otation) is a lightweight data-interchange format, derived from JavaScript, but used by many programming languages. JSON builds universal data structures.</p> + +<p>See <a href="/en-US/docs/Glossary/JSON">JSON</a> and {{jsxref("JSON")}} for more details.</p> + +<h3 id="More_objects_in_the_standard_library">More objects in the standard library</h3> + +<p>JavaScript has a standard library of built-in objects.</p> + +<p>Please have a look at the <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects">reference</a> to find out about more objects.</p> + +<h2 id="Determinare_il_tipo_utilizzando_loperatore_typeof">Determinare il tipo utilizzando l'operatore <code>typeof</code></h2> + +<p>L'operatore <code>typeof</code> può aiutarti a trovare il tipo di dato assegnato alla tua variabile.</p> + +<p><span class="tlid-translation translation" lang="it"><span title="">Si prega di leggere la <a href="/en-US/docs/Web/JavaScript/Reference/Operators/typeof">pagina di riferimento</a> per maggiori dettagli e casi limite.</span></span></p> + +<h2 id="Specifiche">Specifiche</h2> + +<table class="standard-table"> + <thead> + <tr> + <th scope="col">Specification</th> + </tr> + </thead> + <tbody> + <tr> + <td>{{SpecName('ESDraft', '#sec-ecmascript-data-types-and-values', 'ECMAScript Data Types and Values')}}</td> + </tr> + </tbody> +</table> + +<h2 id="Vedi_anche">Vedi anche</h2> + +<ul> + <li><a class="link-https" href="https://github.com/nzakas/computer-science-in-javascript/">Nicholas Zakas collection of common data structure and common algorithms in JavaScript.</a></li> + <li><a href="https://github.com/monmohan/DataStructures_In_Javascript" title="https://github.com/monmohan/DataStructures_In_Javascript">Search Tre(i)es implemented in JavaScript</a></li> +</ul> |