Well, I'm starting to talk.
Λcrlf º?¹º2016/7/31 21:55:27
Well, give me an example of a language.
Λcrlf º?¹º2016/7/31 21:55:39
This is called JS, well, you don't have to name it first.
Λcrlf º?¹º2016/7/31 21:56:06
First, the "stuff" in the machine.
Λcrlf º?¹º2016/7/31 21:56:34
"Things" a total of six kinds, which is a general classification,
Λcrlf º?¹º2016/7/31 21:57:11
The first one is called undefined.
Λcrlf º?¹º2016/7/31 21:57:25
It literally means "undefined."
Λcrlf º?¹º2016/7/31 21:57:56
In fact, all the undefined is the same thing, we call him undefined
Λcrlf º?¹º2016/7/31 21:58:19
A thing that we're not interested in.
Λcrlf º?¹º2016/7/31 21:58:34
The second is very similar to it.
Λcrlf º?¹º2016/7/31 21:58:54
It's just a different meaning, it's called nothingness, null.
Λcrlf º?¹º2016/7/31 21:59:21
All null is the same thing.
Λcrlf º?¹º2016/7/31 21:59:56
The third is called a Boolean, well, it's a name, a scientist, like a logic family.
Λcrlf º?¹º2016/7/31 22:00:18
All of the booleans have two things in total.
Λcrlf º?¹º2016/7/31 22:00:26
One is true, one is False
Λcrlf º?¹º2016/7/31 22:01:04
The distinction is true, and false. You can think of as "meeting expectations" and "not meeting expectations"
Λcrlf º?¹º2016/7/31 22:01:18
We're going to use it when we make decisions.
Λcrlf º?¹º2016/7/31 22:02:04
The fourth type is called string, which literally means a string, with a line meaning
Λcrlf º?¹º2016/7/31 22:02:37
is actually some words
Λcrlf º?¹º2016/7/31 22:03:11
The inside of a unit is a character, can be English letters, kanji, or punctuation, or something
Λcrlf º?¹º2016/7/31 22:03:50
In fact, this is most of the case, the individual rare words are expressed in two units
Λcrlf º?¹º2016/7/31 22:04:13
For example, some ancient or some small state of the text, will use two units
Λcrlf º?¹º2016/7/31 22:04:57
For example, "Hello" is a string of length 2, and "Hello" is a string of length 5.
Λcrlf º?¹º2016/7/31 22:05:16
That sort of
Λcrlf º?¹º2016/7/31 22:05:27
The fifth category is called number.
Λcrlf º?¹º2016/7/31 22:06:01
Can be a positive number, can be a negative number
Λcrlf º?¹º2016/7/31 22:06:15
Ah, because of the computer's design limitations, it has a precision limit
Λcrlf º?¹º2016/7/31 22:07:01
For example, you want to say 1. 0000 (100 x 0) 0005
Λcrlf º?¹º2016/7/31 22:07:16
is not possible, most likely to be used as a means of
Λcrlf º?¹º2016/7/31 22:07:36
And, in particular, there are a few special numbers.
Λcrlf º?¹º2016/7/31 22:07:40
Including:
Λcrlf º?¹º2016/7/31 22:07:44
-0
Λcrlf º?¹º2016/7/31 22:07:55
+inf (positive Infinity)
Λcrlf º?¹º2016/7/31 22:08:02
-inf (Negative infinity
Λcrlf º?¹º2016/7/31 22:08:20
There is also a magic number called Nan (invalid number)
Λcrlf º?¹º2016/7/31 22:08:43
Like 1 divided by 0, you get positive infinity.
Λcrlf º?¹º2016/7/31 22:09:14
LOG10 (-2) got Nan
Λcrlf º?¹º2016/7/31 22:09:34
3 divided by 0, you get negative infinity.
Λcrlf º?¹º2016/7/31 22:10:11
It's a bit strange anyway.
Λcrlf º?¹º2016/7/31 22:10:18
There's a magical nature in it.
Λcrlf º?¹º2016/7/31 22:10:27
NaN is not equal to oneself ...
Λcrlf º?¹º2016/7/31 22:10:32
It's not equal to anything.
Λcrlf º?¹º2016/7/31 22:11:11
The sixth category is object, object, domestic translation into objects
Λcrlf º?¹º2016/7/31 22:11:38
Unlike the first five types
Λcrlf º?¹º2016/7/31 22:11:45
It was made in the field.
Λcrlf º?¹º2016/7/31 22:12:16
So you'll have a sense of how to count.
Λcrlf º?¹º2016/7/31 22:12:32
I think the total number of objects inside the system is fixed.
Λcrlf º?¹º2016/7/31 22:12:42
It's more magical.
Λcrlf º?¹º2016/7/31 22:12:48
It has an internal structure.
Λcrlf º?¹º2016/7/31 22:13:14
The internal structure stores the correspondence between key and value.
Λcrlf º?¹º2016/7/31 22:14:06
{' name ': ' Xue Two dog ', ' age ': 20, ' villain ': true}
Λcrlf º?¹º2016/7/31 22:14:12
This is an object
Λcrlf º?¹º2016/7/31 22:15:17
Key is the string represented in the previous
Λcrlf º?¹º2016/7/31 22:15:26
The value is six kinds can be
Λcrlf º?¹º2016/7/31 22:15:52
This correspondence in an object will have several, can be added to delete the modified
Λcrlf º?¹º2016/7/31 22:15:52
This correspondence in an object will have several, can be added to delete the modified
Λcrlf º?¹º2016/7/31 22:16:15
The first section is finished, is there any problem?
Programming from Scratch (excerpt from chat history)
