四十分鐘JavaScript快速入門 | 無廢話且清晰流暢 | 手敲鍵盤 ...
// The test is note.
// Date 2023.09.05?
// Night?
// 你好，世界！
console.log("hello world!");
// var 全局變量
// let 局部變量
let age=30;
console.log(age);
//const aae;XXXXXXXd
// const 定義的變量此后不能修改
const media = 40;
//media = 50;
console.log(media);
// 數(shù)據(jù)的基本類型
let ade;
ade = 'a';
console.log(ade);
const me = "wdasdw";
console.log(me);
const name1 = "woder";
console.log(name1);
const raer = undefined;
console.log(raer);
const iscook = false;
console.log(iscook);
const isfile = true;
console.log(isfile);
const num1 = 1;
console.log(num1);
const num2 = 2.2;
console.log(num2);
console.log(typeof isfile);
console.log(typeof num1);
const unnum=null;
console.log(unnum);
console.log(typeof unnum);
console.log(typeof raer);
// confirm(typeof num1);?
// confirm 彈出
// 控制臺“+”輸出
console.log("hello"+' '+"world");
const usname ="Make";
const age1 = 30;
// 控制臺輸出模塊化
console.log(`My name is ${usname} and I am ${age1}`);
// 定義字符串
const s1 = "Hello world";
// 長度
console.log(s1.length);
// 大寫
console.log(s1.toUpperCase());
// 小寫
console.log(s1.toLowerCase());
console.log(s1.substring(0,5));
console.log(s1.split(""));
console.log(s1.split(", "));
// 數(shù)組
const num123=new Array(1,2,3,4,5,6,7,8,9);
console.log(num123);
// 數(shù)組的簡單定義
const number = ["asd0",'dwad','dwadasufg',true,null,10];
console.log(number);
console.log(number[0]);
// 在末尾加上
number.push("NewAdd");
console.log(number);
// 在頭部加上
number.unshift("Fornt");
console.log(number);
// 刪除末尾的
// number.pop();
console.log(number);
// 判斷數(shù)據(jù)是否為數(shù)組
console.log(Array.isArray('hello'));
console.log(Array.isArray(number));
// 得到索引
console.log(number.indexOf("asd0"));
// 數(shù)組的更多操作可看js文檔
// 對象
const person ={
??firstName:"Make",
??lastName:"Dan",
??age:30,
??hobbies:["Music","Movies","Sports"],
??address:{
????street:"50 main St",
????city:"WuHan",
????state:"MA",
??},
};
console.log(person);
console.log(person.firstName);
console.log(person.address.street);
// 抽象剝離
const {firstName, lastName ,address:{city},} = person;
console.log(firstName);
console.log(city);
// 添加屬性
person.email = "Make@mail.com";
console.log(person);
// 對象數(shù)組
let result = [
??{
????id:1,
????subject: 'math',
????score: 10,
????isGood:false,
??},
??{
????id:2,
????subject: 'chinese',
????score: 20,
????isGood:false,
??},
??{
????id:3,
????subject: 'english',
????score: 30,
????isGood:true,
??}
];
// 下標
console.log(result[1].subject);
// 對象數(shù)組轉(zhuǎn)化為JSON
const resultJSON = JSON.stringify(result);
console.log(resultJSON);
// if
const xx=4;
// === 考慮數(shù)據(jù)類型 == 不考慮
if (xx === 10){
??console.log("xx is 10");
} else{
??console.log("xx is not 10")
}
if (xx == 10){
??console.log("xx is 10");
}
if (xx > 10){
console.log("xx > 10");
}
const yy =11;
if (yy > 5 || yy > 10){
console.log("xx > 5 or yy > 10");
}
if (yy > 100 && yy > 10){
??console.log("xx > 100 and yy > 10");
??}
// 三目運算符
const xxx=10;
const color = xxx > 10 ? 'red' : 'blue';
console.log(color);
// switch
switch(color){
??case 'red':
????console.log("color is red");
????break;
??case 'blue':
????console.log("color is blue");
????break;
??default:
????console.log("color is Not red or blue");
}
// for and while
for (let i =0;i<10;i++){
??console.log(i);
}
console.log("-----");
let i = 0;
while (i < 10) {
??console.log(i);
??i+=2;
}
let result1s = [
??{
????id:1,
????subject: 'math',
????score: 10,
????isGood:false,
??},
??{
????id:2,
????subject: 'chinese',
????score: 20,
????isGood:false,
??},
??{
????id:3,
????subject: 'english',
????score: 30,
????isGood:true,
??}
];
// 循環(huán)打印result1s中的每一項 類似于python的for x in xs():
for (let result1 of result1s){
??console.log(result1);
}
