Console Learner — An interactive JavaScript course.

4.1 Plain Objects

var obj = { a: 'value', b: 123, c: null }

Object instances are basically ordered sets of named values (properties). See 1.2 Object Types for some common built-in object types.
["a", "b", "c"]
Property names can be listed with the built-in Object.keys() function. See also 2.6 Loops & Iteration for iteration over object properties.
Property access is an O(1) (constant time) operation, making any object a candidate lookup table. See 2.2 Property Access for details.
function toString() {
    [native code]
All objects also have some built-in non-enumerable properties, such as toString, valueOf and hasOwnProperty. These typically contain functions that operate on the object, also known as methods. See the Object instance properties for a compete list.
"[object Object]"
The built-in toString() method works for all objects. But the default implementation isn't all that exciting.
{ a: 1 } === { a: 1 }
Also worth noting is that object instances are never equal unless it is actually the same instance.

The console allows you to interact with the course material and examples. Use the following keys:

A special logging function is also available:

Need more magic? Check out the other developer tools on this site.