'use strict' error example

HTML

<script src="https://getfirebug.com/firebug-lite-debug.js"></script>

JavaScript

(() => {
    // Strict mode makes assignments which would otherwise silently fail to throw an exception. 
    'use strict';
    try {
        const undefined = 666; // throws a TypeError
    } catch(error) {
        console.error(error)
    }
    console.log('Is this read?');
})();