Let you understand the main points of typescript in vernacular (III)

Three object scene

General object .（ It doesn't include methods ）

Same as before , Let's not directly constrain what's in the object , There will always be data before type restrictions .

At this point, go back and add type constraints .（ Specifically demonstrated an error type ）

There's another problem here , Here we use semicolons to separate the types of each attribute . It's not necessary , You can limit the type of attribute by multiline constraints .

Object containing method

Four . Interface interface

Interface scenario 1

As usual , Add specific constraints to existing data and then go back . You can use it here Function This keyword defines the attribute value of an object as a function .

Still use colons : Keyword to constrain .

Scenario 2 of interface ( Inherit extends)

For example, we now have an extra interface To constrain new objects

But we found that ,person2Style This constraint format is the same as the previous one person1Style Many are the same , Is there any way we can directly reuse the same , Add what you want separately ？ It can be used here extends Keyword to implement . It is also relatively easy to implement , If there are no additional attributes you want to add , Then we can

Four . Special expansion of objects ( Yuan Zu )

Just heard this word, I was stunned , Martial arts novel yuan Taizu ？

In fact, after in-depth understanding, you will know that it is just to limit the number of your array and the type of the corresponding value of the corresponding index position . for instance , For example, I now have an array of numeric types , as follows ：

It's the same as writing data , Count the number of data in the array , Properties and values are constrained .

5、 ... and . Enumeration type enum

This attribute actually specifies some constants used . The simplest example ：

We now have a function , We already know that it accepts string parameters ： If we write like this

It seems that some goals have been achieved , But we just want it to accept On (up) Next (down) Left (left) Right (right) Parameters , Then we can use enum, Use it to define some constants .

We give changeDirection The parameters of this function are defined as Direction This enum type ,
Then this is the constraint

And you can call this... Like an object enum type , as follows ：