This site is mobile accessible. Press the "Tap Here" button to use a smaller font-size.

Smartphone icons created by Freepik - Flaticon

JS Arrays

If you use a named index when accessing an array, JavaScript will redefine the array to a standard object, and some array methods and properties will produce undefined or incorrect results.

const person = [];
person["firstName"] = "John";
person["lastName"] = "Doe";
person["age"] = 46; 
document.getElementById("demo").innerHTML =
person[0] + " " + person.length;