Front-End/자바스크립트

자바 스크립트 공부

shoney9254 2021. 5. 3. 23:55
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패스트캠퍼스 [Node 웹 프로그래밍 올인원 패키지 Online] 강의를 기반으로 공부하기 위해 작성한 글입니다. 부족한 설명이나 내용에 대해 말씀해 주시면 수정 및 추가하겠습니다. 

 

 

        //1. 기본자료형 (동적언어이기 때문에 var로 시작)

        console.log("■■■1.기본자료형■■■")

        var a = '123';

        console.log(a);

        var b = null;

        console.log(b);

        var c = undefined;

        console.log(c);

        // console.log(f); //레퍼런스 에러 

 

        //2. 배열

        console.log("■■■2.배열■■■")

        var vlist = ["Hello",24,"node.js","2222"]

        console.log(vlist[0]);

        console.log(vlist);

        console.log(vlist.indexOf("2222"))

        for(var i=0;i<vlist.length;i++){

            console.log(vlist[i]);

        }



        //3. 반복문

        console.log("■■■3.반복문■■■")

        document.write("■■■3.반복문■■■")

        for(var i=0;i<5;i++){

            document.write('<br>')

            document.write('[for] 반복문 : '+i)

        }

        

        var i =0;

        while(i<5){

            document.write('<br>')

            document.write('[while] 반복문 : '+i)

            i++;

        }

 

        var i =0;

        do{

            document.write('<br>')

            document.write('[DoWhile] 반복문 : '+i)

            i++;

        }while(i<5)

        

        for(var i =2i<=3 ; i++){

            for(var j=1j<=9j++){

                document.write('<br>')

                document.write(i+'x'+j+'='+i*j)

            }

        }



        //4-1. 함수

        console.log("■■■4-1.함수■■■")

        function test(ab){

            console.log("입력인자 a : "+a);

            console.log("입력인자 b : "+b);

        }

        test(10,"인자");

 

        function sum(ab){

            return a+b;

        }

        console.log(sum(1,2));

        

        var sum2 = function(a,b){

            return a+b;

        }

        console.log(sum2(1,2));



        //4-2. 객체 함수

        console.log("■■■4-2.객체 함수■■■")

        function Car(a,b,c){

            this.name = a;  //this.을 사용하면 public  변수

            this.color = b;

            var move = c;   //this.을 사용안하면 private 변수

        }

 

        var hyun = new Car("그랜저","흰색","전진");

        console.log(hyun.name);   //public 변수

        console.log(hyun.color);  //public 변수

        console.log(hyun.move);   //private 변수

        console.log(hyun);  

        var canival = new Car("카니발","검은색","후진");

        console.log(canival.name);

        console.log(canival.color);

        console.log(canival.move);

        console.log(canival);



        //5. 프로토타입

        console.log("■■■5.프로토타입■■■")

        function Car2(a,b){

            this.name = a;  

            this.color = b;

        }

        Car2.prototype.move = function(){

            console.log(this.name + "차이고 "this.color +"입니다.")

        }

        var hyun2 = new Car2("그랜저","흰색");

        var canival2 = new Car2("카니발","검은색");

        hyun2.move();

        canival2.move();

 

        

        var abb = [1,2,3,4,10];

        console.log(typeof(abb));

        Array.prototype.print = function(){

            for(var i=0;i<this.length;i++){

                console.log(this[i]);

            }

        }

        abb.print();



        //6. 리터럴객체

        console.log("■■■6.리터럴객체■■■")

        var a = {

            'a': 120,

            'b': 'hello',

            'c': function(){

                this.a++;

                console.log('print')

            }

        }

        

        console.log(a.a);

        a.c();

        console.log(a.a);

        console.log(a.b);

 

        console.log(typeof(a));   //a 타입을 조회하면 Object

 

        Object.prototype.sumtest = function(){   //Object에 function추가

            console.log(this.a +20);

        }

        a.sumtest();



        //7. 조건문

        console.log("■■■7.조건문■■■")

        var j = 13;

        ifj < 10){

            console.log('10보다 작습니다.')

        }

        else if(j < 20){

            console.log('20보다 작습니다.')

        }

        else{

            console.log('20보다 큽니다.')

        }

 

        var k = '5'

        ifk ===5){ // false

            console.log('숫자 5입니다.')

        }

        ifk ==='5'){ // true

            console.log('문자 5입니다.')  

        }

 

        var h = '6'

        ifh ==6){ // true

            console.log('숫자 6입니다.')  

        }

        ifh =='6'){ // true

            console.log('문자 6입니다.')

        }

 

        // Switch문은 일치하는 값을 주로 사용

        switch("yello"){

            case "blue":

                console.log('파란색');

                break;

            case "green":

                console.log('초록색');

                break;

            default:

                console.log('모두아님');

        }

 

        function myNum(num){

            if(num<10)

                return "10보다 작음"

            else

                return "10보다 큼"

        }

        console.log(myNum(11));

        




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