Editing CSV file with Bangle.js v2

Thank you @Gordon and @halemmerich for your help.

I actually really like the staging file idea. It seems to work well:

FULL_DATA = 'full_log.csv';
STAGING_FILE = 'staging_file.csv';

const CSVLogger = {
  
  addLog: (col1, col2, col3) => {
    const line = `${col1},${col2},${col3}\n`;
    
    // Add staged string to full data file
    var stagedString = require("Storage").read(STAGING_FILE);
    if (stagedString) {
      fullData = require("Storage").open(FULL_DATA, "a");
      fullData.write(stagedString);
    }
    
    // Replace the staged file with the new line
    require("Storage").erase(STAGING_FILE);
    require("Storage").write(STAGING_FILE, line);      
  },

  getLastLog: () => {
    var stagedString = require("Storage").read(STAGING_FILE);
    return stagedString ? stagedString.trim().split(",") : null;
  },
  
  deleteLastLog: () => {
    require("Storage").erase(STAGING_FILE);
  },
  
  editLastLog: (col1, col2, col3) => {
    const line = `${col1},${col2},${col3}\n`;
  
    require("Storage").erase(STAGING_FILE);
    require("Storage").write(STAGING_FILE, line);      
  },
  
  // Save staged line to full file when ready to export data
  commitLastLog: () => {
    var stagedString = require("Storage").read(STAGING_FILE);
    
    if (stagedString) {
      // Add old string to full data file
      fullData = require("Storage").open(FULL_DATA, "a");
      fullData.write(stagedString);
    }
    
    require("Storage").erase(STAGING_FILE);

  },
  
  // For debugging
  showBothFiles: () => {
    
    var fullData = require("Storage").open(FULL_DATA, "r");
    fullString = fullData.read(1000);
    print("Full File:\n" + fullString);
    
    var stagedString = require("Storage").read(STAGING_FILE);
    print("Staged File:\n" + stagedString + "\n");

  }
    
};


CSVLogger.addLog('a', 'b', 'c');

CSVLogger.editLastLog('1', '2', '3');

CSVLogger.deleteLastLog();

I'd only be logging a few dozen times per day, so I don't think flash writes should be a big deal.

It's probably not necessary for my project, but it would be cool to have a more general solution for deleting multiple last lines in sequence, which might require something more like what Gordon was saying with rewriting the whole file, or appending the DELETE_LAST_LINE multiple times.