비동기 함수

    
      async function greet() {
        return 'Hello, world!';
      }

      greet().then((message) => {
        console.log(message); // 출력: Hello, world!
      });
    
  

    
      function delay(ms) {
        return new Promise((resolve) => setTimeout(resolve, ms));
      }

      async function greet() {
        await delay(2000);
        return 'Hello, world!';
      }

      async function displayGreeting() {
        const message = await greet();
        console.log(message); // 출력: Hello, world! 2초 후
      }

      displayGreeting();
    
  

    
      function fetchData1() {
        return new Promise((resolve) => setTimeout(() => resolve('Data 1'), 1000));
      }

      function fetchData2() {
        return new Promise((resolve) => setTimeout(() => resolve('Data 2'), 2000));
      }

      async function fetchAllData() {
        const data1 = await fetchData1();
        console.log(data1); // 출력: Data 1 (1초 후)

        const data2 = await fetchData2();
        console.log(data2); // 출력: Data 2 (2초 후)
      }

      fetchAllData();
    
  

    
      function fetchData1() {
        return new Promise((resolve) => setTimeout(() => resolve('Data 1'), 1000));
      }

      function fetchData2() {
        return new Promise((resolve) => setTimeout(() => resolve('Data 2'), 2000));
      }

      async function fetchAllData() {
        const [data1, data2] = await Promise.all([fetchData1(), fetchData2()]);
        console.log(data1); // 출력: Data 1 (2초 후)
        console.log(data2); // 출력: Data 2 (2초 후)
      }

      fetchAllData();
    
  

    
      function fetchDataWithError() {
        return new Promise((resolve, reject) => setTimeout(() => reject('Error occurred'), 1000));
      }

      async function fetchData() {
        try {
          const data = await fetchDataWithError();
          console.log(data);
        } catch (error) {
          console.error('Error:', error); // 출력: Error: Error occurred (1초 후)
        }
      }

      fetchData();
    
  

    
      class DataFetcher {
        async fetchData() {
          const data = await new Promise((resolve) => setTimeout(() => resolve('Fetched Data'), 1000));
          return data;
        }
      }

      const fetcher = new DataFetcher();
      fetcher.fetchData().then((data) => {
        console.log(data); // 출력: Fetched Data (1초 후)
      });
    
  

    
      async function* asyncGenerator() {
        let i = 0;
        while (i < 3) {
          await new Promise((resolve) => setTimeout(resolve, 1000));
          yield i++;
        }
      }

      async function iterateAsyncGenerator() {
        for await (let value of asyncGenerator()) {
          console.log(value); // 출력: 0, 1, 2 (1초 간격)
        }
      }

      iterateAsyncGenerator();