null and undefined null is a language keyword and undefined is a predefined global object.
undefined represents a system level, unexpected or error-like absence of value.
nullrepresents program-level, normal or expected absence of value.
When writing programs yourself always use null.
global object When the JavaScript interpreter starts, it creates a new global object and gives it an initial set of properties.
In client-side JavaScript, the window object serves as the global object.
Do you think Computer Science equals building websites and mobile apps?
Are you feeling that you are doing repetitive and not so intelligent work?
Are you feeling a bit sick about reading manuals and copy-pasting code and keep poking around until it works all day long?
Do you want to understand the soul of Computer Science?
If yes, read SICP!!!
Streams can also be infinite, let’s look at some examples.
Chapter 1 All day long we seemed to dawdle through a country which was full of beauty of every kind.
dawdle: to do something or go somewhere very slowly, taking more time than is necessary.
Stop dawdling! You’ll be late for school!
They are picturesque, but do not look prepossessing.
prepossessing: interesting, attractive, or impressive:
He wasn’t a very prepossessing sort of person. The box didn’t look very prepossessing, but the necklace inside was beautiful.
Do you think Computer Science equals building websites and mobile apps?
Are you feeling that you are doing repetitive and not so intelligent work?
Are you feeling a bit sick about reading manuals and copy-pasting code and keep poking around until it works all day long?
Do you want to understand the soul of Computer Science?
If yes, read SICP!!!
Let’s do one more exercise.
Exercise 3.51: In order to take a closer look at delayed evaluation, we will use the following procedure, which simply returns its argument after printing it: (define (show x) (display-line x) x)
Do you think Computer Science equals building websites and mobile apps?
Are you feeling that you are doing repetitive and not so intelligent work?
Are you feeling a bit sick about reading manuals and copy-pasting code and keep poking around until it works all day long?
Do you want to understand the soul of Computer Science?
If yes, read SICP!!!
To test our knowledge, let’s do some exercises from the book.
