JavaScript: The Good Parts: The Good Parts

by Douglas Crockford

Unlike many other languages, blocks in JavaScript do not create a new scope, so variables should be defined at the top of the function, not in blocks.

Attempting to retrieve values from undefined will throw a TypeError exception. This can be guarded against with the && operator:

e.g. flight.equipment && flight.equipment.model Crockford, Douglas. JavaScript: The Good Parts (Kindle Location 449). O'Reilly Media. Kindle Edition.

The function object created by a function literal contains a link to that outer context. This is called closure. This is the source of enormous expressive power.

There are four patterns of invocation in JavaScript: the method invocation pattern, the function invocation pattern, the constructor invocation pattern, and the apply invocation pattern. The patterns differ in how the bonus parameter this is initialized.

Avoid creating functions within a loop. It can be wasteful computationally,and it can cause confusion,