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JavaScript

Checking the Type of the Object

/*
'typeof' and 'instanceof' isn't a reliable method to find 
out the object class, so this is a function that does this in a more trustable way.
*/

function is(type, obj) {
    var clazz = Object.prototype.toString.call(obj).slice(8, -1);
    return obj !== undefined && obj !== null && clazz === type;
}

is('String', 'test'); // true
is('String', new String('test')); // true
https://snippets.siftie.com/embed/c99a9d81bf8dbebb4eb349a1d00c1fe0/
/raw/c99a9d81bf8dbebb4eb349a1d00c1fe0/
c99a9d81bf8dbebb4eb349a1d00c1fe0
js
JavaScript
12
2019-03-20T01:25:04
True
False
False
/api/public/snipt/48139/
-946
<table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><a href="#L-1"> 1</a> <a href="#L-2"> 2</a> <a href="#L-3"> 3</a> <a href="#L-4"> 4</a> <a href="#L-5"> 5</a> <a href="#L-6"> 6</a> <a href="#L-7"> 7</a> <a href="#L-8"> 8</a> <a href="#L-9"> 9</a> <a href="#L-10">10</a> <a href="#L-11">11</a> <a href="#L-12">12</a></pre></div></td><td class="code"><div class="highlight"><pre><span></span><span id="L-1"><a name="L-1"></a><span class="cm">/*</span> </span><span id="L-2"><a name="L-2"></a><span class="cm">&#39;typeof&#39; and &#39;instanceof&#39; isn&#39;t a reliable method to find </span> </span><span id="L-3"><a name="L-3"></a><span class="cm">out the object class, so this is a function that does this in a more trustable way.</span> </span><span id="L-4"><a name="L-4"></a><span class="cm">*/</span> </span><span id="L-5"><a name="L-5"></a> </span><span id="L-6"><a name="L-6"></a><span class="kd">function</span> <span class="nx">is</span><span class="p">(</span><span class="nx">type</span><span class="p">,</span> <span class="nx">obj</span><span class="p">)</span> <span class="p">{</span> </span><span id="L-7"><a name="L-7"></a> <span class="kd">var</span> <span class="nx">clazz</span> <span class="o">=</span> <span class="nb">Object</span><span class="p">.</span><span class="nx">prototype</span><span class="p">.</span><span class="nx">toString</span><span class="p">.</span><span class="nx">call</span><span class="p">(</span><span class="nx">obj</span><span class="p">).</span><span class="nx">slice</span><span class="p">(</span><span class="mi">8</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">);</span> </span><span id="L-8"><a name="L-8"></a> <span class="k">return</span> <span class="nx">obj</span> <span class="o">!==</span> <span class="kc">undefined</span> <span class="o">&amp;&amp;</span> <span class="nx">obj</span> <span class="o">!==</span> <span class="kc">null</span> <span class="o">&amp;&amp;</span> <span class="nx">clazz</span> <span class="o">===</span> <span class="nx">type</span><span class="p">;</span> </span><span id="L-9"><a name="L-9"></a><span class="p">}</span> </span><span id="L-10"><a name="L-10"></a> </span><span id="L-11"><a name="L-11"></a><span class="nx">is</span><span class="p">(</span><span class="s1">&#39;String&#39;</span><span class="p">,</span> <span class="s1">&#39;test&#39;</span><span class="p">);</span> <span class="c1">// true</span> </span><span id="L-12"><a name="L-12"></a><span class="nx">is</span><span class="p">(</span><span class="s1">&#39;String&#39;</span><span class="p">,</span> <span class="k">new</span> <span class="nb">String</span><span class="p">(</span><span class="s1">&#39;test&#39;</span><span class="p">));</span> <span class="c1">// true</span> </span></pre></div> </td></tr></table>
"Object Type", Javascript, Typeof