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syntactic sugar async & await _ clear style of using promise :) 1. async function fetchUser(){ //if) do network request in 10secs.. return 'ellie'; } const user = fetchUser(); console.log(user); //promise function fetchUser(){ return new Promise((resolve, reject)=>{ //do network request in 10secs.. resolve('ellie'); }); } const user = fetchUser(); user.then(console.log); console.log(user); //asy..

'use strict'; Promise is a JavaScript object for asynchronous operation : 비동기 간편처리obj 1) State: pending -> fulfilled or rejected 2) Producer vs Consumer 1. Producer _ when new Promise is created, the executor runs automatically. const promise = new Promise((resolve, reject) => { //doing some heavy work(network, read files) console.log('doing something...'); setTimeout(()=>{ //resolve('ellie'); r..

'use strict'; JavaScript is synchronous. (동기적_작성순서에 따름) Execute the code block by orger after hoisting. hoisting: var, function declaration (함수 선언들이 자동적으로 가장 위로 올라감 / 코드순서대로 실행) console.log('1'); //1 //지정한 시간이 지나면 callback함수 호출 setTimeout(function(){ console.log('2'); },1000);//1초 후 browser가 출력 //간략히 setTimeout(()=> console.log('2'),1000); console.log('3'); //1,3,2 Synchronous callback function ..

HTTP: hyperText Transfer Protocol _ client와 server의 소통 AJAX( Asynchronous JavaScript And XML ) - XHR( XMLHttpRequest ): 브라우저 api obj, 서버에 data요청, 수령 - fetch() API (ie X) - JSON( JavaScript Object Notation ): ECMAScript 3rd 1999 에서 영감을 받아 생성됨 - Object( key; value } - simplest data interchange format - lightweight text-based struncture - easy to read - key-value pairs - used for serialization and ..

Q1. make a string out of an array { const fruits = ['apple', 'banana', 'orange']; const resule = fruits.join(); console.log(result); //apple.banana,orange const resule = fruits.join('^'); //구분자 추가 console.log(result); //apple^banana^orange } Q2. make an array out of a string { const fruits = '🍎, 🥝, 🍌, 🍒'; const result = fruits.split(','); //구분자 전달하기(필수) console.log(result); //["🍎","🥝","🍌","🍒"] c..

JS = dynamically typed language 1. Declaration const arr1 = new Array(); const arr2 = [1,2]; 2. Index position const fruits = ['🍎','🍌']; console.log(fruits);//['🍎','']; console.log(fruits.length);//2 console.log(fruits['key']);//key에 상응하는 value 받음 console.log(fruits[0]);//🍎 console.log(fruits[1]);//🍌 console.log(fruits[2]);//undefined console.log(fruits[fruits.length-1]);//마지막 요소 console.clear()..

one of the JS's data types a collection of related data and/or functionality. Nearly all objects in JS are instances of Object. object = {key:value}; const name = 'ellie'; const age= 4; print(name, age); function print(name, age) { console.log(name); console.log(age); } //간략히 function print(person) { console.log(person.name); console.log(person.age); } const ellie = {name: 'ellie', age: 4}; prin..

'use strict' class person{ name; age;//속성(field) speak();//행동(method) } class = fields + methods class: template / declare once / no data in ex) 붕어빵틀 object: instance of a class / created many times / data in ex) 팥붕어빵, 슈크림붕어빵 object-oriented programming class: template object: instance of a class javascript classes - introduced in ES6 - syntactical sugar over prototype-based inheritance 1. Class..

Function - fundamental building block in the program - subprogram can be used multiple times - performs a task or calculates a value 1. Function declaration - function name(param1, param2) {body.. return;} - one function === one thing - naming: doSomething, command, verb ex) createCardAndPoint -> createdcard, createPoint - function is object in JS_ 변수할당가능, parameter전달, function return o function..

1. String concatenation console.log('my'+'cat'); console.log('1'+2); console.log(`string literals: 1 +2 = ${1 + 2}`); string literals 장점_ 줄바꿈이나 중간에 ''를 이용해도 그대로 문자열로 변환됨 (＼' : 문자열 ＼n : 줄바꿈 ＼t : tab) 2. Numeric operators console.log(1+1);//add console.log(1-1);//substract console.log(1*1); //multiply console.log(1/1); //divide console.log(1%1); //remainder console.log(1**1); //exponentiation 3. I..