How to connect button to local storage?

I am a beginner and learning using tutorials. This tutorial involves using an API to display pictures. I have included a modal that has a button.

My question is, how would I make the button connect with local storage so it could save the image that is clicked to favourites?

Do I have the right idea in having a function on the button, adding event listener click to add to favourites?

Appreciate any help and examples, thanks.

https://jsfiddle.net/neg4byd5

      <div id="myModal" class="modal">
        <span class="close">&times;</span>
        <img class="modal-content" id="img01">
        <span><button>Add To Favourites</button></span>
        <div id="caption"></div>
      </div>  

// Save Text
    const saveText = document.createElement("p");
    saveText.classList.add("clickable");
    if (page === "results") {
      saveText.textContent = "Add To Favorites";
      saveText.setAttribute("onclick", `saveFavorite('${result.url}')`);
    } else {
      saveText.textContent = "Remove Favorite";
      saveText.setAttribute("onclick", `removeFavorite('${result.url}')`);
    }


// Update the DOM
function updateDOM(page) {
  // Get favorites from local storage
  if (localStorage.getItem("nasaFavorites")) {
    favorites = JSON.parse(localStorage.getItem("nasaFavorites"));
  }
  imagesContainer.textContent = "";
  createDOMNodes(page);
  showContent(page);
}


// Add result to favorites
function saveFavorite(itemUrl) {
  // Loop through the results array to select favorite
  resultsArray.forEach((item) => {
    if (item.url.includes(itemUrl) && !favorites[itemUrl]) {
      favorites[itemUrl] = item;
      // Show save confirmation for 2 seconds
      saveConfirmed.hidden = false;
      setTimeout(() => {
        saveConfirmed.hidden = true;
      }, 2000);
      // Set Favorites in Local Storage
      localStorage.setItem("nasaFavorites", JSON.stringify(favorites));
    }
  });
}

// Remove item from favorites
function removeFavorite(itemUrl) {
  if (favorites[itemUrl]) {
    delete favorites[itemUrl];
    localStorage.setItem("nasaFavorites", JSON.stringify(favorites));
    updateDOM("favorites");
  }
}

// On Load
getNasaPictures();