copyValuesToRange returns nothing if startColumn is integer - google-apps-script

Question

Writing a script where a cell with a formula is overwritten with value shown in the same cell. The following code WORKS (however formatted for readability):
var TargetHistorySheetRow = 95; //some arbitrary integer
var HistorySheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("History");
HistorySheet.getRange(TargetHistorySheetRow, HistorySheet.getRange("1:1").getValues()[0].indexOf("Allocated")+1)
.copyValuesToRange(
HistorySheet,
HistorySheet.getRange("1:1").getValues()[0].indexOf("Allocated")+1,
HistorySheet.getRange("1:1").getValues()[0].indexOf("Allocated")+1,
TargetHistorySheetRow,
TargetHistorySheetRow
);
There is a repeating piece of code throughout (HistorySheet.getRange("1:1").getValues()[0].indexOf("Allocated")+1;) for finding a specific column number dynamically. For readibility, I moved this snippet to a variable and used the variable throughout instead. The following update DOES NOT WORK and changes the target cell to a blank
var TargetHistorySheetRow = 95; //some arbitrary integer
var HistorySheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("History");
var HistorySheetAllocatedColumn = HistorySheet.getRange("1:1").getValues()[0].indexOf("Allocated")+1;
HistorySheet.getRange(TargetHistorySheetRow, HistorySheetAllocatedColumn)
.copyValuesToRange(
HistorySheet,
HistorySheetAllocatedColumn,
HistorySheetAllocatedColumn,
TargetHistorySheetRow,
TargetHistorySheetRow
);
However, if I change only the startColumn parameter of copyValuesToRange back, it WORKS again:
HistorySheet.getRange(TargetHistorySheetRow, HistorySheetAllocatedColumn)
.copyValuesToRange(
HistorySheet,
HistorySheet.getRange("1:1").getValues()[0].indexOf("Allocated")+1,
HistorySheetAllocatedColumn,
TargetHistorySheetRow,
TargetHistorySheetRow
);
Changing that parameter to a static value (eg: 7), doesn't work either. What's going on here?

Answer 1

This appears to be a bug!
The behaviour you describe here is very interesting. When you call Range.copyValuesToRange(sheet, column, columnEnd, row, rowEnd), according to the documentation, the column, columnEnd, row and rowEnd parameters should all be Integers.
Now after some testing, you can see that the following line returns number:
typeof HistorySheet.getRange("1:1").getValues()[0].indexOf("ColumnHeaderC")
As does:
typeof HistorySheet.getRange("1:1").getValues()[0].indexOf("ColumnHeaderC") + 1
However when you log HistorySheetTargetColumn and HistorySheet.getRange("1:1").getValues()[0].indexOf("ColumnHeaderC") + 1 separately, you get the following result:
var HistorySheetTargetColumn = (HistorySheet.getRange("1:1")
.getValues()[0]
.indexOf("ColumnHeaderC") + 1);
Logger.log('variable = ' + HistorySheetTargetColumn); // => variable = 3
Logger.log('method call = ' + HistorySheet.getRange("1:1")
.getValues()[0]
.indexOf("ColumnHeaderC") + 1);
// => method call = 21
You can see that the 21 concatenation happens because HistorySheet.getRange("1:1").getValues()[0].indexOf("ColumnHeaderC") is being evaluated as a string before the + operator, meaning that after the + 1 the value becomes 21 and not 3, as it should be if it was being evaluated as an integer.
It therefore appears that when you use HistorySheetTargetColumn in .copyValuesToRange() is is re-evaluating HistorySheet.getRange("1:1").getValues()[0].indexOf("ColumnHeaderC") + 1 each time, getting 2 from the indexOf() return as a string, and then concatenating the 1 at the end. This is why your cell is evaluating to be blank - because Cell A21 is blank.
Workaround:
You can fix this in the mean time by adding parenthesis around HistorySheet.getRange("1:1").getValues()[0].indexOf("ColumnHeaderC") + 1 on assignment:
var HistorySheetTargetColumn = (HistorySheet.getRange("1:1")
.getValues()[0]
.indexOf("ColumnHeaderC") + 1);
Reporting the Issue:
I have taken the liberty of reporting this on Google's Issue Tracker for you, detailing the behaviour:
Range.copyValuesToRange(sheet, column, columnEnd, row, rowEnd) reading string instead of integer
You can hit the ☆ next to the issue number in the top left on the page which lets Google know more people are encountering this and so it is more likely to be seen to faster.
References:
Google Apps Script - Range.copyValuesToRange(sheet, column, columnEnd, row, rowEnd)
w3schools - JavaScript Array indexOf() Method
MDN web docs - Arithmetic operators
Google's Issue Tracker
Range.copyValuesToRange(sheet, column, columnEnd, row, rowEnd) reading string instead of integer