Revision 1068554 of TypeError: "x" is not a constructor

<div>{{jsSidebar("Errors")}}</div>

<h2 id="Message">Message</h2>

<pre class="syntaxbox">
TypeError: "x" is not a constructor

TypeError: Math is not a constructor
TypeError: JSON is not a constructor
TypeError: Symbol is not a constructor
TypeError: Reflect is not a constructor
TypeError: Intl is not a constructor
TypeError: SIMD is not a constructor
TypeError: Atomics is not a constructor
</pre>

<h2 id="Error_type">Error type</h2>

<p>{{jsxref("TypeError")}}</p>

<h2 id="What_went_wrong">What went wrong?</h2>

<p>There was an attempt to use an object or a variable as a constructor, but that object or variable is not a constructor. See {{Glossary("constructor")}} or the <a href="/en-US/docs/Web/JavaScript/Reference/Operators/new"><code>new</code> operator</a> for more information on what a constructor is.</p>

<p>There are many global objects, like {{jsxref("String")}} or {{jsxref("Array")}}, which are constructable using <code>new</code>. However, some global objects are not and their properties and methods are static. The following JavaScript standard built-in objects are not a constructor: {{jsxref("Math")}}, {{jsxref("JSON")}}, {{jsxref("Symbol")}}, {{jsxref("Reflect")}}, {{jsxref("Intl")}}, {{jsxref("SIMD")}}, {{jsxref("Atomics")}}.</p>

<p><a href="/en-US/docs/Web/JavaScript/Reference/Statements/function*">Generator functions</a> cannot be used as constructors either.</p>

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

<h3 id="Invalid_cases">Invalid cases</h3>

<pre class="brush: js example-bad">
var Car = 1;
new Car();
// TypeError: Car is not a constructor

new Math();
// TypeError: Math is not a constructor

new Symbol();
// TypeError: Symbol is not a constructor

function* f() {};
var obj = new f;
// TypeError: f is not a constructor
</pre>

<h3 id="A_car_constructor">A car constructor</h3>

<p>Suppose you want to create an object type for cars. You want this type of object to be called <code>car</code>, and you want it to have properties for make, model, and year. To do this, you would write the following function:</p>

<pre class="brush: js">
function Car(make, model, year) {
  this.make = make;
  this.model = model;
  this.year = year;
}
</pre>

<p>Now you can create an object called <code>mycar</code> as follows:</p>

<pre class="brush: js">
var mycar = new Car("Eagle", "Talon TSi", 1993);</pre>

<h2 id="See_also">See also</h2>

<ul>
 <li>{{Glossary("constructor")}}</li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Operators/new"><code>new</code> operator</a></li>
</ul>