安装
运用npm安装
- npm install -g typescript
- npx tsc
类型
- number
- boolean
- string
- literal
- 类型的并集
- any类型
- undefined类型
# 常量不能改变
const ttt = "123"
# 指定类型后，能改变，但是不能改变类型,未指定类型会自动推断类型
let amount:number = 123
# 可以定义多个类型,后续若修改此变量也只能在定义的变量类型中
let amount:number|string = 123
# 可指定变量值数组，定义的变量值只能在此当中
let amount:123|321|'123'|'321' = 123
# 定义变量为任意类型
let amount:any = 123
# 定义为undefined，则只能为undefined
let amount:undefined = undefined
异常
所有判断等于的情况尽量用三个等于，判断不相等的时候使用两个等于
for (let i =0;i<100;i++){
sum+=i
try{
if (i % 18 === 0){
throw `caonima ${i}`
}
}catch(err){
console.log(err)
}
}
# out put
[LOG]: "caonima 0"
[LOG]: "caonima 18"
[LOG]: "caonima 36"
[LOG]: "caonima 54"
[LOG]: "caonima 72"
[LOG]: "caonima 90"
[LOG]: 4950
特有类型(枚举)
定义
enum HttpStatus {
OK,
Not_FOUND,
INTERNAL_SERVER_ERROR
}
function processHTTPStatus(s: HttpStatus){
// 状态码
console.log(s)
// 也可以直接打印枚举定义的名字
console.log(HttpStatus[s]
}
processHTTPStatus(HttpStatus.INTERNAL_SERVER_ERROR)
编译后的JS代码
var HttpStatus;
(function (HttpStatus) {
HttpStatus[HttpStatus["OK"] = 0] = "OK";
HttpStatus[HttpStatus["Not_FOUND"] = 1] = "Not_FOUND";
HttpStatus[HttpStatus["INTERNAL_SERVER_ERROR"] = 2] = "INTERNAL_SERVER_ERROR";
})(HttpStatus || (HttpStatus = {}));
function processHTTPStatus(s) {
console.log(s);
}
processHTTPStatus(HttpStatus.INTERNAL_SERVER_ERROR);
自己定义状态码
可以设置为数字或字符串
enum HttpStatus {
OK = 200,
Not_FOUND = 400,
INTERNAL_SERVER_ERROR = 500
}