1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
| let age: number = 25;
const age = 25;
let scores: number[] = [12, 13];
let entry: [string, number] = ["1", 2];
// return type can be void
function sum(a:number=5, b?: number): number {
console.log(`ID: ${a}`);
return a + b;
}
interface User {
id: string;
age?: number;
readonly name: string;
}
type ID = string | number;
let userId: ID = "ab";
type Status = "pending" | "active";
enum Color {
Red = "Red",
Green = "Green"
}
// 类型推断: 函数变量需要写类型，函数内大部分不需要写
const map = new Map<string, number>([
["key1", "value1"], // like tuple
["key2", "value2"]
]);
map.set("a", 9);
map.forEach((v, k) => {console.log(`${k}:${v}`)}); // recommend
for(const [k, v] of map){
if(typeof v == 'string')
console.log(`${k}:${v}`);
}
// class: readonly, private, protected, public, constructor
// class Dob extends Animal
for (let i=0; i < 5; i++) {
let b = i + 1;
}
const nums = [1, 2, 3];
nums.forEach((num) => {let t = num + 1;}); // recommend
// 剩余函数
function sum2(...nums: number[]){
let s = 0;
nums.forEach(num => {s += num;});
for (const num of nums) {
s += num;
}
return s;
}
let bb = sum2(2, 3, 4);
// 匿名函数
const add = (a: number, b:number) => {
return a + b;
}
let cc = nums.join("");
|
