module
- components/HelloWorld.vue
import { a } from "@/modules";
import b from "@/modules";
export default {
mounted() {
console.log(a);
b();
}
};
复制代码- modules/index.js
let a = 'JonSnow'
let b = 'Cercei'
export {
a
}
export default () => console.log(b);
复制代码- components/HelloWorld.vue
import b from "@/module";
export default {
mounted() {
b().then(res => {
console.log(res);
});
}
};
复制代码- modules/index.js
export default () => new Promise((resolve, reject) => {
setTimeout(() => {
resolve('es6 module')
}, 200)
})
复制代码class
class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}
say() {
console.log(`${this.name}'s age is ${this.age}`);
}
}
class Student extends Person {
constructor(name, age, sex) {
super(name, age);
this.sex = sex;
}
saySex() {
console.log(
`${this.name}'s age is ${this.age} and his sex is ${this.sex}`
);
}
}
let JonSnow = new Student("JonSnow", 21, "男");
JonSnow.say();
JonSnow.saySex();
console.log(JonSnow);
console.log(JonSnow instanceof Student);
console.log(JonSnow instanceof Person);
复制代码includes && indexOf
let arr = [1, 2, 3];
console.log(arr.includes(1));
console.log(arr.indexOf(100));
复制代码全局作用域与函数作用域
var a = 12;
function fn() {
console.log(a);
var b = 13;
if (true) {
var c = 14;
console.log(b);
}
console.log(c);
}
fn();
console.log(c);//报错
复制代码函数执行完后，变量就被销毁了
使用undefined传参
function myFunction(x = 1, y = 2, z = 3) {
console.log(x, y, z);//1,7,9
}
myFunction(undefined, 7, 9);
复制代码参数运算
function myFunction(x, y, z = x + y) {
console.log(x, y, z);//1,2,3
}
fn(1, 2);
复制代码push
let a1 = [1];
let a2 = [2, 3, 4];
// a1.push(2, 3, 4);
a1.push(...a2);
console.log(a1);
复制代码忽略数组中的某些值
let [a, , b] = [1, 2, 3];
console.log(a); //1
console.log(b); //3
复制代码使用展开语法
let [a, ...b] = [1, 2, 3];
console.log(a); // 1
console.log(b); //[2,3]
复制代码let [a, , ...b] = [1, 2, 3, 4, 5];
console.log(a); //1
console.log(b); //[3,4,5]
复制代码let [a, b, c = 3] = [1, 2];
console.log(a); //1
console.log(b); //2
console.log(c); //3
复制代码function myFunction([a, b, c = 3] = [1, 2, 3]) {
console.log(a, b, c);//1 2 3
}
myFunction();
复制代码function myFunction([a, b, c = 3] = [1, 2, 3]) {
console.log(a, b, c);//1 2 3
}
myFunction(undefined);
复制代码