Here's a preview of the spreadsheet I'm editing in Google Drive:The transaction type cell has a value of debit if the row is for an expense, and credit if it is income.I would like a script to go through each row, and add a minus sign before the value in the amount column, if the value in the transaction Type column has a value of debit.
Google sheets: conditionally change sign of decimal value in cell for each row
google spreadsheets;google apps script
Maybe give this a try:function onOpen() {SpreadsheetApp.getUi().createMenu('Custom Menu')    .addItem('Make Negative', 'makeNegative')    .addToUi();}function makeNegative() {var res = [],    range = SpreadsheetApp.getActiveSheet().getRange('D2:E'),    val = range.getValues()        .forEach(function (r, i) {            r[0] = r[1] === 'debit' && r[0] > 0 && typeof r[0] === 'number' ? r[0] * -1 : r[0]            res.push(r)        })    range.setValues(res);}Add above script to the script editor and run onOpen() by clicking the 'play' button. Then go back to the sheet, where you should see a newly created menu-item 'Custom Menu'. From there click on 'Make negative' and see if this works.