How to track content when line is clicked and line is left

Question

I am writing a VSCode Extension that tracks code progress in a .csv file. For now everytime I change from one line to another it gets tracked as a change into the .csv file, even if the content in the line did not change. The .csv file should only track changes and should ignore if a line is still the same.

My current code snippet looks like this:

function trackLineChanges(event: vscode.TextEditorSelectionChangeEvent) {
  const line = event.selections[0].active.line;

  if (previousLine !== undefined && previousLine !== line) {
    const timestamp = Date.now();
    const content = editor!.document.lineAt(previousLine).text;
    const isEmptyLine = content.trim() === "";
    trackedChanges.push({
      timestamp,
      content,
      line: previousLine + 1,
      isEmptyLine,
    });
    console.log(`Line ${previousLine + 1} changed:`, content, timestamp);
    saveChangesToCSV();
  }
  previousLine = line;
}

My idea was to check the content of the line, when the line gets clicked. The content at the click is then saved into a variable. Then there is a second check of the content when the user leaves the line and switches to another line.

I tried to sum my idea up in some general pseudocode:

function trackLineChanges(event: vscode.TextEditorSelectionChangeEvent) {
  const line = event.selections[0].active.line;
  let contentClicked = "";
  let contentLeft = "";

  if (cursor focus on line){
     contentClicked = text in line when the line got clicked
  }

  if (cursor focus is not on line anymore){
     contentLeft = text in line when the line is not in focus anymore
  }

  if (contentClicked !== contentLeft){
    write to .csv
  }