Add datetime/uuid stamp at bottom on completion

Add stamp on completion. This is useful if the lab is being
used in a class, to provide evidence if people simply copy
the same file to show they did the work.

Signed-off-by: David A. Wheeler <[email protected]>

Author: david-a-wheeler

docs/labs/checker.js

@@ -216,6 +216,16 @@ function runCheck() {
 
     if (isCorrect && (oldGrade !== newGrade)) {
         // Hooray! User has a newly-correct answer!
+
+        // Set `correctStamp` id (if present) with timestamp and UUID
+        // This makes it easy to detect someone simply copying a final result.
+        correctStamp = document.getElementById('correctStamp');
+        if (correctStamp) {
+            let timeStamp = (new Date()).toISOString();
+            let uuid = crypto.randomUUID();
+            correctStamp.innerHTML = `${timeStamp} ${uuid}`;
+	}
+
         // Use a timeout so the underlying page will *re-render* before the
 	// alert shows. If we don't do this, the alert would be confusing
 	// because the underlying page would show that it wasn't completed.

docs/labs/csp1.html

@@ -408,6 +408,7 @@ <h2>Interactive Lab (<span id="grade"></span>)</h2>
 <button type="button" id="resetButton">Reset</button>
 <button type="button" id="giveUpButton">Give up</button>
 <br><br>
+<pre id="correctStamp"></pre>
 <textarea id="debugData" rows="20" cols="70" readonly style="display: none;">
 </textarea>
 </form>

docs/labs/hello.html

@@ -169,6 +169,7 @@ <h2>Interactive Lab (<span id="grade"></span>)</h2>
 <button type="button" id="resetButton">Reset</button>
 <button type="button" id="giveUpButton">Give up</button>
 <br><br>
+<pre id="correctStamp"></pre>
 <textarea id="debugData" rows="20" cols="70" readonly style="display: none;">
 </textarea>
 </form>

docs/labs/input1.html

@@ -225,6 +225,7 @@ <h2>Interactive Lab (<span id="grade"></span>)</h2>
 <button type="button" id="resetButton">Reset</button>
 <button type="button" id="giveUpButton">Give up</button>
 <br><br>
+<pre id="correctStamp"></pre>
 <textarea id="debugData" rows="20" cols="70" readonly style="display: none;">
 </textarea>
 </form>

docs/labs/input2.html

@@ -216,6 +216,7 @@ <h2>Interactive Lab (<span id="grade"></span>)</h2>
 <button type="button" id="resetButton">Reset</button>
 <button type="button" id="giveUpButton">Give up</button>
 <br><br>
+<pre id="correctStamp"></pre>
 <textarea id="debugData" rows="20" cols="70" readonly style="display: none;">
 </textarea>
 </form>