The default point of this in JS and how to modify it to 2021.11.09

Under each scenario this Default point of ：

- Point to... In a normal function window

- Point to... In the event function Event source

- In the timer, point to widnow

- Point to... In the self executing function window

- Point to... In the object object

- There is no... In the arrow function this Point to the Search for superior

modify this The way to point ：

1） Function name . call（ To change the direction , Parameters 1, Parameters 2,.......);

2） Function name . apply（ To change the direction ,【 Parameters 1, Parameters 2,.......】);

3） Function name . bind（ To change the direction , Parameters 1, Parameters 2,.......) ;

 

difference ：

call and apply The difference between ： The format of parameter transfer is different ,apply In the form of an array .

bind and call/apply The difference between ：call/apply Focus on borrowing , There must be a calling procedure , The essence is modification this, and bind Just

It's for modification this, Do not call （ It can be called manually , Back plus （） ）

bind The meaning of ： In some cases , The function does not execute immediately , It's called back at some point Now bind More appropriate , As determined

Timer function .