Article directory
1, limited attributes
object qualification
This input must only have a name attribute of type string, otherwise an error will be reported.
/*对象限制*/
function sayName1(obj: {
name: string }) {
console.log("我的名字叫：" + obj.name);
}
sayName1({
name: "张三"})
Effect:
我的名字叫：张三
Interface restrictions
The function is the same as above.
interface People {
name: string
}
function sayName2(obj: People) {
console.log("我的名字叫：" + obj.name);
}
sayName2({
name: "李四"})
Effect:
我的名字叫：李四
some spelling
Optional
None.
As a type, there will be code hints.
interface People {
name: string
age?:number
}
read-only
This is the general qualification of the property
interface People {
readonly id:number
name: string
age?:number
}
3, limited to other
function type
You can limit the return of the function.
The parameter name is not required, but the type needs to be consistent.
interface sayName {
(obj: {
name: string }): void
}
let a: sayName
a = function (s: {
name: string }): void {
console.log(s.name)
}
array type
The value type of an array can be qualified.
interface MyStringArray {
[index: number]: string;
}
let myArray: MyStringArray;
myArray = ["AAA", "BBB"];
let myStr: string = myArray[0];
4, limited class
Simple to use
A class implements an interface and must have all its properties and methods.
interface User {
name:string
sayName():void
}
class MyUser implements User {
name:string;
sayName() {
console.log(this.name)
}
}
let a=new MyUser()
a.name="( ⊙ o ⊙ )啊！"
a.sayName()
inheritance relationship
An interface can inherit from multiple interfaces. Limits will be superimposed.
Interfaces can also inherit from classes.
5, fool the compiler (not recommended)
Tell the compiler that this object belongs to this interface and doesn't need to be checked.
type assertion
After an assertion, the compiler doesn't check for it.
interface People {
name: string
}
function sayName2(obj: People) {
console.log(1)
}
sayName2({
} as People)
attribute qualification
Relax the attribute requirements, and the compiler will not report an error.
interface People {
name?: string
[propName: string]: any
}
function sayName2(obj: People) {
console.log(1)
}
sayName2({
age:3})