add visual flash feedback on click-to-copy elements

When a user clicks to copy text, the clicked element now briefly
inverts (foreground/background swap) and fades back over 500ms,
providing immediate localized feedback. The existing flash message
is retained for accessibility.

Closes #100

src/popup/styles/main.css

@@ -15,20 +15,22 @@
     --color-section: #dddddd;
 }
 
+@keyframes copy-flash {
+    0% {
+        background-color: var(--color-fg);
+        color: var(--color-bg);
+    }
+    100% {
+        background-color: transparent;
+        color: inherit;
+    }
+}
+
+.copy-flash {
+    animation: copy-flash 500ms ease-out;
+}
+
 body {
     width: 396px;
     overflow-x: hidden;
 }
-
-/* Copy-flash feedback: inverts colors then fades back */
-.copy-flash-active {
-    background-color: var(--color-fg) !important;
-    color: var(--color-bg) !important;
-    transition: none;
-}
-
-.copy-flash-fade {
-    transition:
-        background-color 300ms ease-out,
-        color 300ms ease-out;
-}

src/popup/views/addressDetail.js

@@ -2,7 +2,7 @@ const {
     $,
     showView,
     showFlash,
-    flashCopyFeedback,
+    flashCopyElement,
     balanceLinesForAddress,
     addressDotHtml,
     addressTitle,
@@ -238,11 +238,12 @@ function renderTransactions(txs) {
 function init(_ctx) {
     ctx = _ctx;
     $("address-full").addEventListener("click", () => {
-        const addr = $("address-full").dataset.full;
+        const el = $("address-full");
+        const addr = el.dataset.full;
         if (addr) {
             navigator.clipboard.writeText(addr);
+            flashCopyElement(el);
             showFlash("Copied!");
-            flashCopyFeedback($("address-full"));
         }
     });
 
@@ -356,20 +357,22 @@ function init(_ctx) {
     });
 
     $("export-privkey-value").addEventListener("click", () => {
-        const key = $("export-privkey-value").textContent;
+        const el = $("export-privkey-value");
+        const key = el.textContent;
         if (key) {
             navigator.clipboard.writeText(key);
+            flashCopyElement(el);
             showFlash("Copied!");
-            flashCopyFeedback($("export-privkey-value"));
         }
     });
 
     $("export-privkey-address").addEventListener("click", () => {
-        const full = $("export-privkey-address").dataset.full;
+        const el = $("export-privkey-address");
+        const full = el.dataset.full;
         if (full) {
             navigator.clipboard.writeText(full);
+            flashCopyElement(el);
             showFlash("Copied!");
-            flashCopyFeedback($("export-privkey-address"));
         }
     });
 

src/popup/views/addressToken.js

@@ -5,7 +5,7 @@ const {
     $,
     showView,
     showFlash,
-    flashCopyFeedback,
+    flashCopyElement,
     addressDotHtml,
     addressTitle,
     escapeHtml,
@@ -314,11 +314,12 @@ function renderTransactions(txs) {
 function init(_ctx) {
     ctx = _ctx;
     $("address-token-full").addEventListener("click", () => {
-        const addr = $("address-token-full").dataset.full;
+        const el = $("address-token-full");
+        const addr = el.dataset.full;
         if (addr) {
             navigator.clipboard.writeText(addr);
+            flashCopyElement(el);
             showFlash("Copied!");
-            flashCopyFeedback($("address-token-full"));
         }
     });
 
@@ -326,8 +327,8 @@ function init(_ctx) {
         const copyEl = e.target.closest("[data-copy]");
         if (copyEl) {
             navigator.clipboard.writeText(copyEl.dataset.copy);
+            flashCopyElement(copyEl);
             showFlash("Copied!");
-            flashCopyFeedback(copyEl);
         }
     });
 
@@ -375,8 +376,8 @@ function init(_ctx) {
         if (copyEl) {
             copyEl.addEventListener("click", () => {
                 navigator.clipboard.writeText(copyEl.dataset.copy);
+                flashCopyElement(copyEl);
                 showFlash("Copied!");
-                flashCopyFeedback(copyEl);
             });
         }
         updateSendBalance();

src/popup/views/confirmTx.js

@@ -15,7 +15,7 @@ const {
     hideError,
     showView,
     showFlash,
-    flashCopyFeedback,
+    flashCopyElement,
     addressTitle,
     addressDotHtml,
     escapeHtml,
@@ -117,8 +117,8 @@ function show(txInfo) {
         if (copyEl) {
             copyEl.onclick = () => {
                 navigator.clipboard.writeText(copyEl.dataset.copy);
+                flashCopyElement(copyEl);
                 showFlash("Copied!");
-                flashCopyFeedback(copyEl);
             };
         }
     } else {

src/popup/views/helpers.js

@@ -76,6 +76,18 @@ function clearFlash() {
     $("flash-msg").textContent = "";
 }
 
+function flashCopyElement(el) {
+    el.classList.remove("copy-flash");
+    // Force reflow so re-adding the class restarts the animation.
+    void el.offsetWidth;
+    el.classList.add("copy-flash");
+    el.addEventListener(
+        "animationend",
+        () => el.classList.remove("copy-flash"),
+        { once: true },
+    );
+}
+
 function showFlash(msg, duration = 2000) {
     clearFlash();
     $("flash-msg").textContent = msg;
@@ -259,26 +271,13 @@ function timeAgo(timestamp) {
     return years + " year" + (years !== 1 ? "s" : "") + " ago";
 }
 
-function flashCopyFeedback(el) {
-    if (!el) return;
-    el.classList.remove("copy-flash-fade");
-    el.classList.add("copy-flash-active");
-    setTimeout(() => {
-        el.classList.remove("copy-flash-active");
-        el.classList.add("copy-flash-fade");
-        setTimeout(() => {
-            el.classList.remove("copy-flash-fade");
-        }, 350);
-    }, 100);
-}
-
 module.exports = {
     $,
     showError,
     hideError,
     showView,
     showFlash,
-    flashCopyFeedback,
+    flashCopyElement,
     balanceLine,
     balanceLinesForAddress,
     addressColor,

src/popup/views/home.js

@@ -2,7 +2,7 @@ const {
     $,
     showView,
     showFlash,
-    flashCopyFeedback,
+    flashCopyElement,
     balanceLinesForAddress,
     isoDate,
     timeAgo,
@@ -88,8 +88,8 @@ function renderActiveAddress() {
             `<a href="${link}" target="_blank" rel="noopener" class="inline-flex items-center">${EXT_ICON}</a>`;
         $("active-addr-copy").addEventListener("click", (e) => {
             navigator.clipboard.writeText(addr);
+            flashCopyElement(e.currentTarget);
             showFlash("Copied!");
-            flashCopyFeedback(e.currentTarget);
         });
     } else {
         el.textContent = "";

src/popup/views/receive.js

@@ -2,7 +2,7 @@ const {
     $,
     showView,
     showFlash,
-    flashCopyFeedback,
+    flashCopyElement,
     formatAddressHtml,
     addressTitle,
 } = require("./helpers");
@@ -61,21 +61,23 @@ function show() {
 }
 
 function init(ctx) {
-    $("receive-address-block").addEventListener("click", (e) => {
+    $("receive-address-block").addEventListener("click", () => {
-        const addr = $("receive-address-block").dataset.full;
+        const el = $("receive-address-block");
+        const addr = el.dataset.full;
         if (addr) {
             navigator.clipboard.writeText(addr);
+            flashCopyElement(el);
             showFlash("Copied!");
-            flashCopyFeedback(e.currentTarget);
         }
     });
 
     $("btn-receive-copy").addEventListener("click", () => {
-        const addr = $("receive-address-block").dataset.full;
+        const block = $("receive-address-block");
+        const addr = block.dataset.full;
         if (addr) {
             navigator.clipboard.writeText(addr);
+            flashCopyElement(block);
             showFlash("Copied!");
-            flashCopyFeedback($("receive-address-block"));
         }
     });
 

src/popup/views/transactionDetail.js

@@ -5,7 +5,7 @@ const {
     $,
     showView,
     showFlash,
-    flashCopyFeedback,
+    flashCopyElement,
     addressDotHtml,
     addressTitle,
     escapeHtml,
@@ -171,8 +171,8 @@ function render() {
         .forEach((el) => {
             el.onclick = () => {
                 navigator.clipboard.writeText(el.dataset.copy);
+                flashCopyElement(el);
                 showFlash("Copied!");
-                flashCopyFeedback(el);
             };
         });
 }
@@ -249,8 +249,8 @@ async function loadCalldata(txHash, toAddress) {
             container.querySelectorAll("[data-copy]").forEach((el) => {
                 el.onclick = () => {
                     navigator.clipboard.writeText(el.dataset.copy);
+                    flashCopyElement(el);
                     showFlash("Copied!");
-                    flashCopyFeedback(el);
                 };
             });
         }

src/popup/views/txStatus.js

@@ -4,7 +4,7 @@ const {
     $,
     showView,
     showFlash,
-    flashCopyFeedback,
+    flashCopyElement,
     addressDotHtml,
     addressTitle,
     escapeHtml,
@@ -77,8 +77,8 @@ function attachCopyHandlers(viewId) {
         .forEach((el) => {
             el.onclick = () => {
                 navigator.clipboard.writeText(el.dataset.copy);
+                flashCopyElement(el);
                 showFlash("Copied!");
-                flashCopyFeedback(el);
             };
         });
 }