🐋 TIL 0204

⬇️ Main Note
https://docs.google.com/document/d/1gK7xsH7GOBUNFVCbZtZ0Z0rL87pw8pvoK0G50tryWZg/edit

🧊 [Open-API]

It is useful when a frontend developer makes a program without any backend developers.
Public API looks like the table below. (github)

• API-key: Exists to prevent million times of requests.
  --> Able to use only when the user signed up to the API and gets the key of it.

import {useEffect, useState} from "react"
import axios from 'axios'

export default function OpenApiPage () {

    const [dogUrl, setDogUrl]= useState("")
    
    useEffect(() => {
        const fetchDog = async () => {
            const result =  await axios.get("https://dog.ceo/api/breeds/image/random")
            //API 사이트 자체를 해줘야함 거기서 message, status 골라서 받아오는것
            setDogUrl(result.data.message)// promise가 뜨게 되는데 이건 비동기형식이라 언젠가 result 화면에 보여줄게 하고 말하는것
                                                //--> 이렇게 안에 함수를 만들어주고 그 안에 넣어줘야 async 사용 가능
        }
        fetchDog()
    }, []) //빈 array는 한번만 실행하고 그 뒤로는 실행 안한다는것

    return (
        <div>
            <div>오픈 API 연습</div>
            <img src={dogUrl} width="50%" height="50%"/>
        </div>
    )
}

---

🎐 [Backend Architecture]

How the Server Structure is Generated

DataBase Structure

DataBase Management System

---

🥣 [Algorithms - Overall]

Factorial!

function solution(a, b) {
    let answer = 0;
    
    for(let i = 0; i<a.length; i++){
        const sum = a[i] * b[i]
        answer += sum
    }
    return answer;
} //같은 배열은 동일한 인덱스로 접근할 수 있다

Removing the Smallest Number

function solution(arr) {
    const answer = []
    
    let min = arr[0]
    for(let i=1;i<arr.length; i++){
        if(min>arr[i]){
            min = arr[i]
        }
    }
    for (let i=0;i<arr.length; i++){
        if(arr[i] !==min){
            answer.push(arr[i])
        }
    }
    return answer.length === 0 ? [-1] : answer
}

Building filter() Method

function myFilter(array, callbackFn) {
    let newArray = [];
    for (let i = 0; i<array.length; i++){
        callbackFn(array[i], i) && newArray.push(array[i])
    }
    return newArray
}