files/ca/web/javascript/referencia/objectes_globals/math/abs/index.html


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---
title: Math.abs()
slug: Web/JavaScript/Referencia/Objectes_globals/Math/abs
translation_of: Web/JavaScript/Reference/Global_Objects/Math/abs
---
<div>{{JSRef("Global_Objects", "Math")}}</div>

<h2 id="Summary" name="Summary">Resum</h2>

<p>La funció <strong><code>Math.abs()</code></strong> retorna el valor absolut d'un nombre. És a dir:</p>

<p><math display="block"><semantics><mrow><mstyle mathvariant="monospace"><mrow><mo lspace="0em" rspace="thinmathspace">Math.abs</mo><mo stretchy="false">(</mo><mi>x</mi><mo stretchy="false">)</mo></mrow></mstyle><mo>=</mo><mrow><mo stretchy="false">|</mo><mi>x</mi><mo stretchy="false">|</mo></mrow><mo>=</mo><mrow><mo>{</mo><mtable columnalign="left left"><mtr><mtd><mi>x</mi></mtd><mtd><mtext>if</mtext><mspace width="1em"></mspace><mi>x</mi><mo>&gt;</mo><mn>0</mn></mtd></mtr><mtr><mtd><mi>0</mi></mtd><mtd><mtext>if</mtext><mspace width="1em"></mspace><mi>x</mi><mo>=</mo><mn>0</mn></mtd></mtr><mtr><mtd><mo>-</mo><mi>x</mi></mtd><mtd><mtext>if</mtext><mspace width="1em"></mspace><mi>x</mi><mo>&lt;</mo><mn>0</mn></mtd></mtr></mtable></mrow></mrow><annotation encoding="TeX">{\mathtt{\operatorname{Math.abs}(x)}} = {|x|} = \begin{cases} x &amp; \text{if} \quad x \geq 0 \\ -x &amp; \text{if} \quad x &lt; 0 \end{cases} </annotation></semantics></math></p>

<h2 id="Syntax" name="Syntax">Sintaxi</h2>

<pre class="syntaxbox"><code>Math.abs(<var>x</var>)</code></pre>

<h3 id="Parameters" name="Parameters">Paràmetres</h3>

<dl>
 <dt><code>x</code></dt>
 <dd>Un nombre.</dd>
</dl>

<h2 id="Description" name="Description">Descripció</h2>

<p>Degut a que <code>abs()</code> és un mètode estàtic de <code>Math</code>, sempre s'utilitza com a <code>Math.abs()</code>, en comptes de com a mètode d'una instància de <code>Math</code> (<code>Math</code> no és un constructor).</p>

<h2 id="Examples" name="Examples">Exemples</h2>

<h3 id="Example:_Math.abs_behavior" name="Example:_Math.abs_behavior">Exemple: Comportament de <code>Math.abs()</code></h3>

<p>Si li passem una string no numèric o bé una variable {{jsxref("undefined")}}/buida retorna {{jsxref("NaN")}}. Passar {{jsxref("null")}} retorna 0.</p>

<pre class="brush: js">Math.abs('-1');     // 1
Math.abs(-2);       // 2
Math.abs(null);     // 0
Math.abs('string'); // NaN
Math.abs();         // NaN
</pre>

<h2 id="Specifications" name="Specifications">Especificacions</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Especificació</th>
   <th scope="col">Estat</th>
   <th scope="col">Comentaris</th>
  </tr>
  <tr>
   <td>ECMAScript 1a Edició.</td>
   <td>Standard</td>
   <td>Definició inicial. Implementat a JavaScript 1.0.</td>
  </tr>
  <tr>
   <td>{{SpecName('ES5.1', '#sec-15.8.2.1', 'Math.abs')}}</td>
   <td>{{Spec2('ES5.1')}}</td>
   <td> </td>
  </tr>
  <tr>
   <td>{{SpecName('ES6', '#sec-math.abs', 'Math.abs')}}</td>
   <td>{{Spec2('ES6')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility" name="Browser_compatibility">Compatibilitat amb navegadors</h2>

<div>{{CompatibilityTable}}</div>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Característica</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Suport bàsic</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Característica</th>
   <th>Android</th>
   <th>Chrome for Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Suport bàsic</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="See_also" name="See_also">Vegeu també</h2>

<ul>
 <li>{{jsxref("Math.ceil()")}}</li>
 <li>{{jsxref("Math.floor()")}}</li>
 <li>{{jsxref("Math.round()")}}</li>
 <li>{{jsxref("Math.sign()")}} {{experimental_inline}}</li>
 <li>{{jsxref("Math.trunc()")}} {{experimental_inline}}</li>
</ul>