Excel JavaScript API Part 5: The large numbers bug

There is currently (JavaScript Excel API set 1.4) a rather nasty bug when writing large integer numbers (anything larger than int32) back to a range.

The JS can correctly read these large numbers – it just silently gets the wrong answer when writing them back.

Testing what works and what does not work

I ran 5 tests:

  1. 9876543210 – a large integer
  2. 9876543210.0 – a large double that can convert to an integer
  3. 9876543210.1 – a large non-integer double
  4. ‘9876543210’ – a large number as a string
  5. “‘9876543210” – a large number as a string prefixed with ‘

The results were:

  1. 1286608618 – wrong
  2. 1286608618 – wrong
  3. 9876543210.1 – correct
  4. 9876543210 – gives a number but the string type has been ignored by Excel
  5. ‘9876543210 – correct – Excel treats this as string because of the ‘

Here is the test code:


async function run() {
try {
await Excel.run(async (context) => {
let sheet = context.workbook.worksheets.getActiveWorksheet();
let rng1 = sheet.getRange("A3");
rng1.values = [[9876543210]];
let rng2 = sheet.getRange("A5");
rng2.values = [[9876543210.0]];
let rng3 = sheet.getRange("A7");
rng3.values = [[9876543210.1]];
let rng4 = sheet.getRange("A9");
rng4.values = [['9876543210']];
let rng5 = sheet.getRange("A11");
rng5.values = [["'9876543210"]];

await context.sync();
});
}
catch (error) {
OfficeHelpers.Utilities.log(error);
}
}

The Hacky Bypass

The real problem of course comes when you use JS to read a range and write it back but you don’t know what the range contains. If it’s a large integer your code is FUBAR.

The only current bypass is to loop through the range values, test for large integers and convert them to string by surrounding with ‘.

Conclusion

I sure hope this gets fixed soon!

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