ES3 inside wording

Anonymous function is not take or need to give him the assignment

of the selected part is called the anonymous function

equal sign is called the assignment

let xxx called the statement

so that this place is three grammar, first declare an anonymous function, then declare a variable xxx, finally put this anonymous function assigned to the variable xxx

es6 arrow function

Arrow function can only do an assignment, I do not declare
this is a standard function of the arrow

2 writing, only one parameter

If only one function, you can not write parentheses

calling it to do the test

3 cases of writing, only one sentence in the body of the function

If the body of the function only one sentence, you can not write braces.
We assume that the function body only return p1 + p2 this sentence

then braces can be omitted out. p1 + p2 will default to return in the past.

Only one parameter, and the only function body is only one sentence

Why is there an arrow function

Function there this is the most difficult of

the arrow does not function inside this

What is this? this is the first argument to call

the reason why there will be a function of the arrow, because this is too hard to use.

ES3 inside how to use this

Before talking about this, talk about the parameters

look at the following code, declare the function, f, call the function f, incoming abc, then the value of p1 is abc

fact p1 is the first argument value of
p1 is the argument of the second value

in It builds argument object before executing the function f, which is a function of two parameters f,

Enter this

Without p1 do not p2, printing out this. This is where does this come about?

For better description, this function on a target

assuming two values p1 and p2

Understand python inside slef

Search python class look at the python's class is how to use the

value of 1 is passed p1. So self where they come from it? ?

Back js

The first parameter is actually a function hi this is also an object 1 corresponds p1,2 corresponding p2 is

what this is it? this is actually a front .hi thing here is that this object

is actually the first parameter this object is hidden.

The same is also here this invisible

summarize

this is always the first argument to call