How is this method using a parameter that is never given a value? : <p>I came across the .every() method today and found this example code to explain how it works:</p>

<pre><code>var ages = [32, 33, 16, 40];

function checkAdult(age) {
    return age &gt;= 18;
}

function myFunction() {
    document.getElementById("demo").innerHTML = ages.every(checkAdult);
}
</code></pre>

<p>The result of <code>myFunction()</code> is <code>false</code>, and I understand what the method is doing (going through each value of the array and checking if the value is <code>&gt;= 18</code>, but I don't understand how the <code>.every()</code> method is able to use the <code>age</code> parameter in its return statement without <code>age</code> being declared in the method call.</p>

<p>Does the method somehow automatically know that it should be referencing the index of the array it's looking at? That's the only explanation I can come up with, but I can't find any explanation of this online.</p>
