User:Ranto2012/沙盒

代码示例

类与继承与多态

class Base {
    name = "base";
    printName() {
        console.log(this.name);
    }
}

class ChildA extends Base {
    name = "a";
}

class ChildB extends Base {
    name = "b";

}

obj1 = new Base();
obj1.printName();

obj2 = new ChildA();
obj2.printName();

obj3 = new ChildB();
obj3.printName();

输出结果：

base
a
b

异步与回调与Promise

function a1() {
    console.log("from a1");
}

function a2() {
    console.log("from a2");
}

function b(cb) {
    setTimeout(() => {
        console.log("from b");
        cb();
    }, 1000)
}

async function c() {
    await new Promise((resolve) => {
        setTimeout(() => {
            console.log("from c");
            resolve();
        }, 1000);
    })
}

function test1() {
    console.log("test1");
    b(a1);
}

async function test2() {
    console.log("test2");
    const p = c();
    a1();
    await p;
    a2();
}

test1()结果：

test1
from b
from a1

test2()结果：

test2
from a1
from c
from a2