JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/cdn.min.js"></script>
<script>
  //******************* Ignore this code ************************** 
  var counter = 0;
  var taskId = null;

  function fakeApiValidator(state) {
    if (window.taskId === 1) {
      return fakeApiValidateCartItemsStateTask1(state);
    }
    if (window.taskId === 2) {
      return fakeApiValidateCartItemsStateTask2(state);
    }
  }

  function fakeApiValidateCartItemsStateTask1(state) {
    return new Promise((resolve) => {
      state.length === 1 && state.includes('Derila') ?
        setTimeout(() => resolve(state), 100) :
        resolve(state);
    });
  }
  
  function fakeApiValidateCartItemsStateTask2(state) {
    return new Promise((resolve, reject) => {
      window.counter++;
      if (window.counter < 3) {
        reject('Network outage!');
      }
      resolve(state);
    });
  }
  //***************************************************************

  Alpine.data('component', function() {
    return {
      cartItemsState: [],
      task: null,
      addCartItem(name) {
        this.addCartItemQueue = this.addCartItemQueue.then(() => {
          const newState = this.cartItemsState.concat(name);

          return fakeApiValidator(newState)
            .catch(() => [])
            .then(response => this.cartItemsState = response);
        });
        
        return this.addCartItemQueue;
      },
      // For the first task you only need to edit addCartItem method. Task 1 simulates 3 addCartItem events that happen in a very short period of time. Expected outcome => ['Derila', 'Nuubu', 'Huusk'].
      task1() {
        this.addCartItemQueue = Promise.resolve();
        this.cartItemsState = [];
        this.task = null;
        window.taskId = 1;
        Promise.all([
          this.addCartItem('Derila'),
          this.addCartItem('Nuubu'),
          this.addCartItem('Huusk')
        ]).then(() => this.task = 1);
      },
      // For the second task you...

CSS

body {
  background: white;
  padding: 20px;
  font-family: Arial, sans-serif;
  background-color: #f0f0f0;
  padding: 20px;
}

.component-container {
  background-color: #fff;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  padding: 20px;
  max-width: 400px;
  margin: 0 auto;
}

.component-container button {
  background-color: #007bff;
  color: #fff;
  padding: 10px;
  border-radius: 4px;
  text-align: center;
  cursor: pointer;
  transition: background-color 0.3s;
  margin-right: 10px;
}

.component-container p {
  font-size: 1.2em;
  margin-bottom: 10px;
  font-weight: bold;
}

.component-container ul {
  list-style-type: none;
  padding: 0;
}

.component-container li {
  padding: 8px;
  border-bottom: 1px solid #ddd;
}

.component-container li:last-child {
  border-bottom: none;
}

.run-test {
  display: flex;
  align-items: center;
  margin-bottom: 10px;
}

.run-test .alert {
  background-color: #f0f0f0 !important;
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 5px;
  text-align: center;
}

.run-test .alert p {
  margin: 0;
  color: #c00;
  font-size: 12px;
}

.run-test .alert p span {
  font-weight: normal;
  color: black;
}

.run-test .success {
  background-color: #9FE582 !important;
  padding: 10px;
  border: 1px solid #ddd;
  border-radius: 5px;
  text-align: center;
}
.run-test .success p {
  margin: 0;
  color: #0B5800;
  font-size: 12px;
}
.run-test .success p span {
  font-weight: normal;
  color: black;
}