范型：支持不特定的类型，要求传入的参数和返回的参数保持一致。
1 基本例子
function identity<T>(arg: T): T {
return arg;
}
let output = identity<string>("myString");
let output = identity("myString");
2 泛型变量
function loggingIdentity<T>(arg: T[]): T[] {
console.log(arg.length); // Array has a .length, so no more error
return arg;
}
// 也可以这样
function loggingIdentity<T>(arg: Array<T>): Array<T> {
console.log(arg.length); // Array has a .length, so no more error
return arg;
}
loggingIdentity(['2'])
3 泛型类
class GenericNumber<T> {
zeroValue: T;
add: (x: T, y: T) => T;
}
let myGenericNumber = new GenericNumber<number>();
myGenericNumber.zeroValue = 0;
myGenericNumber.add = function(x, y) { return x + y; };
4 泛型约束
interface Lengthwise {
length: number;
}
function loggingIdentity<T extends Lengthwise>(arg: T): T {
console.log(arg.length); // Now we know it has a .length property, so no more error
return arg;
}
loggingIdentity(3); // Error, number doesn't have a .length property
5 范型接口
interface Fn<T>{
(value:T):T;
}
function print<T>(value:T):T{
return value;
}
const printData:Fn<string>=print;
