<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>

    <style type="text/css">
      body {
        font-family: sans-serif;
      }

      .page {
        display: flex;
        min-height: 100vh;
        align-items: stretch;
      }

      .textContainer {
        width: 100%;
        display: flex;
        flex-direction: column;
        font-weight: bold;
        font-size: 4rem;
        text-align: center;
        letter-spacing: -0.2rem;
        font-weight: bolder;
        line-height: 1;
        justify-content: center;
      }

      .gradientText {
        position: relative;
        background-image: linear-gradient(to right, #000, #000);
        z-index: 1;
        -webkit-background-clip: text;
        color: transparent;
      }

      .gradientText::before {
        position: absolute;
        top: 0;
        right: 0;
        bottom: 0;
        left: 0;
        z-index: -1;
        transition: opacity 0.5s linear;
        opacity: 0;
        -webkit-background-clip: text;
      }

      /* 자바스크립트로 클래스 추가 */
      .transitionOn::before {
        opacity: 1;
      }

      .gradient_HTML::before {
        content: "HTML";
        background-image: linear-gradient(to right, #007cf0, #00dfd8);
      }
      .gradient_CSS::before {
        content: "CSS";
        background-image: linear-gradient(to right, #7928ca, #ff0080);
      }
      .gradient_Javascript::before {
        content: "Javascript";
        background-image: linear-gradient(to right, #ff4d4d, #f9cb28);
      }
    </style>
  </head>
  <body>
    <div class="page">
      <div class="textContainer">
        <span id="text_1" class="gradientText gradient_HTML">HTML</span>
        <span id="text_2" class="gradientText gradient_CSS">CSS</span>
        <span id="text_3" class="gradientText gradient_Javascript"
          >Javascript</span
        >
      </div>
    </div>

    <script type="text/javascript">
      (function () {
        const persist = 2500;
        const textIds = ["text_1", "text_2", "text_3"];

        const turnOnTransition = (el) => {
          el.classList.add("transitionOn");
          setTimeout(() => {
            el.classList.remove("transitionOn");
          }, persist);
        };

        const runTransition = (id) => {
          const el = document.getElementById(id);

          if (el) {
            setTimeout(() => {
              turnOnTransition(el);

              setInterval(() => {
                turnOnTransition(el);
              }, persist * textIds.length);
            }, 1);
          }
        };

        textIds.forEach((id, index) => {
          setTimeout(() => {
            runTransition(id);
          }, index * persist);
        });
      })();
    </script>
  </body>
</html>

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.