JavaScript.md

HTML is bones CSS is style JS is interactive

How to JS

Data Types

• Bool
• Number
• String
• Null
• Undefined

always use "===" to compare

//compute GCD of 2 nums
const GCD = (a, b) => {
    while (b !==0) {
        const temp = b;
        b = a % b;
        a = temp;
    }
    return a;
}

Defining Variables

let myBool = "Yes";
let myNum = 12;
let myString = "Hello World!";

const ans = 8964;   //we cannot redefine it

null - no value; undefined - we have declared a var but have not assigned it a value

console.log - printf in Cpp

const a = 5;
const b = 10;

console.log(`a * b = ${a * b}`);

alert("something"); //pop-up

array.push() //insert to the last elem array.pop() //delete the last elem

for ... of ...

const sb = ['1', '2', '3,'];

for (const 2b of sb){
    const nc  = "CNM" + 2b;
    console.log(nc);
}

Object is a collection of name: value pairs

const myCar = {
    make: "Benz";
    model: "S680";
    year: "2024";
    color: "Black";
};

console.log(myCar.make);

Copy arr If we use

let arr = [1, 2];
let copyArr = arr;
//copyArr和arr指向同一个内存地址

Actually we use

let arr = [1, 2];
let copyArr = [...arr];

let obj = {name : "Su Biyang"};
let copyObj = {...obj};

JS Func

Syntax: (parameters) => { body }