<div class="section">
  <button id="btn">
    <p id="btnText">Submit</p>
    <div class="checked">
      <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 50 50">
        <path fill="transparent" d="M14.1 27.2l7.1 7.2 16.7-16.8"></path>
      </svg>
    </div>
  </button>
</div>
* {
  margin: 0;
  padding: 0;
}

.section {
  display: flex;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100vh;
  background: #e3ebfe;
}
button {
  position: relative;
  width: 250px;
  height: 75px;
  border: 0;
  outline: none;
  background: #2b2d42;
  color: #fff;
  font-size: 22px;
  border-radius: 40px;
  text-align: center;
  box-shadow: 0 6px 20px -5px rgba(0, 0, 0, 0.4);
  overflow: hidden;
  cursor: pointer;
}
.checked {
  width: 75px;
  height: 75px;
  border-radius: 40px;
  box-shadow: 0 0 12px -2px rgba(0, 0, 0, 0.2);
  position: absolute;
  top:0;
  right: -40px;
  opacity: 0;
  /background: #d90429;
}
.checked svg {
  width: 40px;
  margin: 20px;
}
.checked path {
  stroke-width: 3;
  stroke: #fff;
  stroke-dasharray: 34;
  stroke-dashoffset: 34;
  stroke-linecap: round;
}
.active {
  background: #d90429;
  transition: 1s;
}
.active p {
  transition: 1s;
  margin-right: 100px;
}
.active .checked {
  opacity: 1;
  transition: 1s;
  right: 0;
}
.active .checked path {
  transition: 1s;
  transition-delay: 1s;
  stroke-dashoffset: 0;
}
var btn = document.getElementById("btn");
var btnText = document.getElementById("btnText");

btn.onclick = function() {
  btnText.innerHTML = "Thanks";
  btn.classList.add("active");
}

External CSS

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External JavaScript

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