Python 与 TypeScript 基础语法对等实现

下面把 Python 开发者最常用 的语言要素——基础类型、控制语句、函数——逐条映射到 TypeScript，给出“最小差异”代码示例。
阅读时可直接复制到 TS Playground 运行验证。

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1️⃣ 基本数字 & 字符串

Python

age: int = 18
price: float = 9.99
name: str = "Alice"
name = "Alice"  # 动态推断
greeting = f"Hello, {name}"  # f-string

TypeScript

const age: number = 18;       // 所有数字都统一为 number
const price: number = 9.99;
const name: string = "Alice";
let name: string = "Alice";
let greeting = `Hello, ${name}`;  // 模板字符串

---

2️⃣ 布尔 & None / null

Python True/False（首字母大写）

flag: bool = True
empty: None = None

TypeScript true/false（小写）

const flag: boolean = true;
const empty: null = null;     // undefined 也可

---

3️⃣ 列表 ↔ 数组

Python 动态类型列表

nums: list[int] = [1, 2, 3]
mixed: list[Any] = [1, "x"]
nums = [1, 2, 3]          # 可混合类型
nums.append("4")          # 允许添加字符串

TypeScript 需统一元素类型

const nums: number[] = [1, 2, 3];
const mixed: (number | string)[] = [1, "x"];
// 或使用泛型写法 Array<number>
let nums: number[] = [1, 2, 3]; // 仅允许数字
nums.push(4);                   // 合法
nums.push("5");                 // 编译报错

---

4️⃣ 元组 ↔ 元组

Python 固定长度，元素类型可混合

coord: tuple[int, int] = (10, 20)
point = (10, "x")  # (int, str)

TypeScript 需明确定义每个位置类型

const coord: [number, number] = [10, 20];
let point: [number, string] = [10, "x"]; 

---

5️⃣ 字典 ↔ 对象 / Map / Record

Python dict 键值对

person: dict[str, int] = {"age": 30}
user = {"name": "Alice", "age": 30}

TypeScript 接口定义结构

// 最常用的对象字面量
const person: Record<string, number> = { age: 30 };

// 如果键固定，可写接口
interface Person { age: number; }
const p: Person = { age: 30 };

interface User {
    name: string;
    age: number;
}
let user: User = { name: "Alice", age: 30 };  

---

6️⃣ 集合 ↔ Set

Python

s: set[int] = {1, 2, 3}

TypeScript

const s: Set<number> = new Set([1, 2, 3]);

---

7️⃣ 控制语句

if / elif / else

Python 缩进控制作用域

if age < 18:
    print("minor")
elif age == 18:
    print("just 18")
else:
    print("adult")

TypeScript 花括号明确作用域

if (age < 18) {
  console.log("minor");
} else if (age === 18) {
  console.log("just 18");
} else {
  console.log("adult");
}

for 循环

Python：for...in 遍历序列

for n in [1, 2, 3]:
    print(n)

TypeScript：类 C 风格或 for...of

// 类 C 循环
for (let i = 0; i < 5; i++) {
  console.log(i);
}

// 遍历数组
for (const n of [1, 2, 3]) {
  console.log(n);
}

while / break / continue

Python

i = 0
while i < 3:
    print(i)
    i += 1

TypeScript

let i = 0;
while (i < 3) {
  console.log(i);
  i += 1;
}

---

8️⃣ 函数

普通函数

Python：动态参数与返回值

def add(a: int, b: int = 0) -> int:
    return a + b

TypeScript：需声明参数和返回类型

function add(a: number, b = 0): number {
  return a + b;
}
// 箭头函数写法
const add2 = (a: number, b = 0): number => a + b;

匿名函数

Python：lambda

square = lambda x: x ** 2

TypeScript：箭头函数

const add2 = (a: number, b = 0): number => a + b;
const square = (x: number): number => x ** 2;

可变参数

Python

def sum_all(*args: int) -> int:
    return sum(args)

TypeScript

function sumAll(...args: number[]): number {
  return args.reduce((a, b) => a + b, 0);
}

关键字参数 / 对象形参

Python：默认值实现可选参数

def greet(name: str, *, greeting: str = "Hello") -> str:
    return f"{greeting}, {name}!"

TypeScript：显式标记 ?

function greet(name: string, { greeting = "Hello" }: { greeting?: string } = {}) {
  return `${greeting}, ${name}!`;
}

---

9️⃣ 类 & 继承

Python

class Animal:
    def __init__(self, name: str) -> None:
        self.name = name

    def speak(self) -> str:
        return f"{self.name} makes a sound"

class Dog(Animal):
    def speak(self) -> str:
        return f"{self.name} barks"

TypeScript

class Animal {
  constructor(public name: string) {}
  speak(): string {
    return `${this.name} makes a sound`;
  }
}

class Dog extends Animal {
  speak(): string {
    return `${this.name} barks`;
  }
}

---

🔟 高级特性对比

1. 类型联合（Union Types）

• Python：Union 类型注解

  from typing import Union
  def parse_input(data: Union[str, int]) -> str:
      return str(data)

• TypeScript：原生联合类型 |

  function parseInput(data: string | number): string {
    return data.toString();
  }  

2. 字面量类型

• Python：通过 Literal 实现

  from typing import Literal
  def set_direction(d: Literal["north", "south"]): ...

• TypeScript：原生支持字面量联合

  function setDirection(d: "north" | "south") { ... }  

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1️⃣1️⃣ 列表推导式 ↔ Array.map/filter/reduce

Python

evens = [x * 2 for x in range(5)]

TypeScript

const evens = Array.from({ length: 5 }, (_, x) => x * 2);

---

1️⃣2️⃣ 模块导出导入

Python

# utils.py
def foo(): ...

# main.py
from utils import foo

TypeScript

// utils.ts
export function foo() {}

// main.ts
import { foo } from './utils';

---

小结速查表

Python	TypeScript	备注
int/float	number	统一
list[T]	T[]	数组
tuple[A, B]	[A, B]	元组
dict[str, T]	Record<string, T>	对象
set[T]	Set<T>	集合
None	null / undefined	二选一
def f(...) -> T	function f(...): T	类型后置
*args	...args: T[]	剩余参数
类继承	class A extends B	相同

把这张表贴墙，日常写 TS 基本不会迷路。祝编码愉快！