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데일리 공부 기록

hands on vue - under the hood(Vue 동작원리, Vue는 어떻게 데이터를 반응형으로 동작하는가)

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1. Javascript는 기본형이 active한 언어가 아니다

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Vue Basics</title>
    <link
      href="https://fonts.googleapis.com/css2?family=Jost:wght@400;700&display=swap"
      rel="stylesheet"
    />
    <link rel="stylesheet" href="styles.css" />
    <script src="https://unpkg.com/vue@next" defer></script>
    <script src="app.js" defer></script>
  </head>
  <body>
    <header>
      <h1>Vue Behind The Scenes</h1>
    </header>
    <section id="app">
      <h2>How Vue Works</h2>
      <input type="text" @input="saveInput">
      <button @click="setText">Set Text</button>
      <p>{{ message }}</p>
    </section>
  </body>
</html>
const app = Vue.createApp({
  data() {
    return {
      currentUserInput: '',
      message: 'Vue is great!',
    };
  },
  methods: {
    saveInput(event) {
      this.currentUserInput = event.target.value;
    },
    setText() {
      this.message = this.currentUserInput;
    },
  },
});

app.mount('#app');

let message = 'Hello';
let longMessage = message + 'World!';

console.log(longMessage); //Hello World! 가 나와야함

message = 'Hello!!!!';    //

console.log(longMessage); //Hello!!!! World! 가 나올 것으로 예상됨
* {
  box-sizing: border-box;
}

html {
  font-family: 'Jost', sans-serif;
}

body {
  margin: 0;
}

header {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.26);
  margin: 3rem auto;
  border-radius: 10px;
  padding: 1rem;
  background-color: #4fc08d;
  color: white;
  text-align: center;
  width: 90%;
  max-width: 40rem;
}

#app {
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.26);
  margin: 3rem auto;
  border-radius: 10px;
  padding: 1rem;
  text-align: center;
  width: 90%;
  max-width: 40rem;
}

#app h2 {
  font-size: 2rem;
  border-bottom: 4px solid #ccc;
  color: #4fc08d;
  margin: 0 0 1rem 0;
}

#app p {
  font-size: 1.25rem;
  font-weight: bold;
  border: 1px solid #4fc08d;
  background-color: #4fc08d;
  color: white;
  padding: 0.5rem;
  border-radius: 25px;
}

#app input {
  font: inherit;
  border: 1px solid #ccc;
}

#app input:focus {
  outline: none;
  border-color: #1b995e;
  background-color: #d7fdeb;
}

#app button {
  font: inherit;
  cursor: pointer;
  border: 1px solid #ff0077;
  background-color: #ff0077;
  color: white;
  padding: 0.05rem 1rem;
  box-shadow: 1px 1px 2px rgba(0, 0, 0, 0.26);
}

#app button:hover,
#app button:active {
  background-color: #ec3169;
  border-color: #ec3169;
  box-shadow: 1px 1px 4px rgba(0, 0, 0, 0.26);
}

js 소스를 살펴보자

 

아래 좌변은 하나의 변수와 문자열로 되어있다.

let message = 'Hello'

let longMessage = message + 'World!' 

 

선언한 이후에 우변의 message를 수정한다.

let message = 'Hello';

let longMessage = message + 'World!' ;

message = 'Hello!!!!';

console.log(longMessage); //Hello!!!! World! 가 아닌 Hello World!가 출력됨