Javascript have objects which can be represented as key-value pair.

The key must be and will be converted to a string. Here is an object

Copy{
 name: "Moo", age: 20
}

You can already represent a Binary Tree by using this notation, though not as pretty as C/C++/Java counterpart.

Copy{
 node: 20,
 left: {
   node: 10,
   left: null,
   right: null
 },
 right: {
   node: 30,
   left: null,
   right: null
 }
}

You can obtain the value of the field using someObject.field or someObject["field"], both are equivalent!.

List and Arrays can be represented using javascript Arrays, however they are also an object. Observe this.

Copyvar myArray = [2,3,5];
myArray[0]; // 2
myArray["0"]; // 2
myArray["push"]; // function push()..... etc etc

Does this means myArray also an object? well yes. It just happened that your browser is smart enough that when you console.log it, it shows the data and hides the methods properly.