Fixes bugs #11777 and #11726, 'outputPrepend' needed to be cleared on each cell execute.

src/client/datascience/interactive-ipynb/nativeEditor.ts

@@ -589,6 +589,11 @@ export class NativeEditor extends InteractiveBase implements INotebookEditor {
                 // Clear the result if we've run before
                 await this.clearResult(cell.id);
 
+                // Clear 'per run' data passed to WebView before execution
+                if (cell.data.metadata.tags !== undefined) {
+                    cell.data.metadata.tags = cell.data.metadata.tags.filter((t) => t !== 'outputPrepend');
+                }
+
                 const code = concatMultilineStringInput(cell.data.source);
                 // Send to ourselves.
                 await this.submitCode(code, Identifiers.EmptyFileName, 0, cell.id, cell.data, undefined, cancelToken);

src/client/datascience/jupyter/jupyterNotebook.ts

@@ -1283,8 +1283,8 @@ export class JupyterNotebookBase implements INotebook {
         trimFunc: (str: string) => string
     ) {
         const data: nbformat.ICodeCell = cell.data as nbformat.ICodeCell;
-        let originalTextLenght = 0;
-        let trimmedTextLenght = 0;
+        let originalTextLength = 0;
+        let trimmedTextLength = 0;
 
         // Clear output if waiting for a clear
         if (clearState.value) {
@@ -1301,32 +1301,36 @@ export class JupyterNotebookBase implements INotebook {
             // tslint:disable-next-line:restrict-plus-operands
             existing.text = existing.text + msg.content.text;
             const originalText = formatStreamText(concatMultilineStringOutput(existing.text));
-            originalTextLenght = originalText.length;
+            originalTextLength = originalText.length;
             existing.text = trimFunc(originalText);
-            trimmedTextLenght = existing.text.length;
+            trimmedTextLength = existing.text.length;
         } else {
             const originalText = formatStreamText(concatMultilineStringOutput(msg.content.text));
-            originalTextLenght = originalText.length;
+            originalTextLength = originalText.length;
             // Create a new stream entry
             const output: nbformat.IStream = {
                 output_type: 'stream',
                 name: msg.content.name,
                 text: trimFunc(originalText)
             };
             data.outputs = [...data.outputs, output];
-            trimmedTextLenght = output.text.length;
+            trimmedTextLength = output.text.length;
             cell.data = data;
         }
 
         // If the output was trimmed, we add the 'outputPrepend' metadata tag.
         // Later, the react side will display a message letting the user know
         // the output is trimmed and what setting changes that.
-        if (trimmedTextLenght < originalTextLenght) {
-            if (!data.metadata.tags) {
-                data.metadata.tags = ['outputPrepend'];
-            } else {
-                data.metadata.tags.push('outputPrepend');
-            }
+        // * If data.metadata.tags is undefined, define it so the following
+        //   code is can rely on it being defined.
+        if (data.metadata.tags === undefined) {
+            data.metadata.tags = [];
+        }
+
+        data.metadata.tags = data.metadata.tags.filter((t) => t !== 'outputPrepend');
+
+        if (trimmedTextLength < originalTextLength) {
+            data.metadata.tags.push('outputPrepend');
         }
     }
 

src/datascience-ui/interactive-common/kernelSelection.tsx

@@ -96,9 +96,9 @@ export class KernelSelection extends React.Component<IKernelSelectionProps> {
             : ImageName.JupyterServerConnected;
     }
 
-    private getMaxWidth(charLenght: number): string {
+    private getMaxWidth(charLength: number): string {
         // This comes from a linear regression
-        const width = 0.57674 * charLenght + 1.70473;
+        const width = 0.57674 * charLength + 1.70473;
         const unit = 'em';
         return Math.round(width).toString() + unit;
     }