12.7 자바스크립트

this와 람다함수

let obj ={
    a:10,
    b:20,
    f1:function(){
        console.log('f1: ', this.a, this.b);
    },
    f2:()=>{
        console.log('f2: ', this.a, this.b);
    },
    f3: function(){
        for( const key in this){
            console.log(key, this[key]);
        }
    }
};

obj.f1();
obj.f2();
obj.f3();

결과값

f1: 10 20

f2: undefined undefined

a 10

b 20

f1 ƒ (){ console.log('f1: ', this.a, this.b); }

f2 ()=>{ console.log('f2: ', this.a, this.b); }

f3 ƒ (){ for( const key in this){ console.log(key, this[key]); } }

 

 

 

병합된 객체

const obj01={
    a:10,
    b:20,

}

const obj02 = {
    c:30,
    d:40,

}

const obj03 = Object.assign(obj01,obj02);

console.log(obj03); //병합된 객체 확인가능

 

결과값

{a: 10, b: 20, c: 30, d: 40}

 

 

 

 

배열

let ar = [10,20.30];
console.log(ar, ar.length);
let br  = Array();

console.log(br, br.length);
let cr = Array(8);
console.log(cr, cr.length);

let dr = Array(2,3,4,5);
console.log(dr,dr.length);

 

 

결과값

(2) [10, 20.3] 2

(0) [] 0

(8) […] 8

(4) [2, 3, 4, 5] 4

 

 

배열 응용

let ar = [10,20,30];

for(const index in ar){
    console.log(index, ar[index]);
}

for(const value of ar){
    console.log(value);
}
ar.forEach(function(){});
ar.forEach(()=> {console.log(1000);});
ar.forEach( (a)=> {console.log(a);});
ar.forEach((v,i)=> {console.log(v,i);})
ar.forEach((a,b,c)=>{
    console.log(a,b,c);
});

 

 

결과값

10
20
30
3
1000
10
20
30
10 0
20 1
30 2
10 0 (3) [10, 20, 30]
20 1 (3) [10, 20, 30]
30 2 (3) [10, 20, 30]

 

 

 

배열 내 객체

let ar = [
    {name:'이순신',
    age : 10},
    {name :'김정희',
    age : 29
},
    {
        name: '성희',
        age:10
    },
];

for(const value of ar){
    //console.log(value);
    console.log(value.name,value['age']);
}

ar.forEach((v,i)=>{
    console.log(v,i);
});

 

결과값

이순신 10

김정희 29

성희 10

 

{name: '이순신', age: 10} 0

{name: '김정희', age: 29} 1

{name: '성희', age: 10} 2

 

 

배열의 toString

let ar = [10,20,30,40];

console.log(1,ar);

let br = ar.toString();

console.log(typeof br, br);

 

결과값

 

 

pop과 push

let ar = [10,20,30,40];

//pop() *

console.log('pop 구현');

let num = ar.pop();

//(method) Array<number>.pop():number | undefined

console.log(3,ar,num);

//push()*

console.log('push 구현');

ar.push(88);

console.log(4,ar);

 

결과값

 

concat

 

let er =[...{},...{}]

 

 

 

 

추후 내용 추가 예정 

to be continue...