Checks if the specified value is undefined.

const isUndefined = val => val === undefined;

isUndefined(undefined); // true

Checks if the specified value is <code class="notranslate">undefined</code>.
<ul>
<li>Use the strict equality operator to check if <code class="notranslate">val</code> is equal to <code class="notranslate">undefined</code>.</li>
</ul>

Value is undefined

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Value is nil

Check if value is of type

Value is null