How to prevent error throwing in Google Apps Script? - google-apps-script

Question

Please see the code herein under:
function binanceOrderBook() {
try {
muteHttpExceptions = true;
var workSpreadsheet = SpreadsheetApp.getActiveSpreadsheet();
var mySheet = workSpreadsheet.getSheetByName('Order Books');
if(mySheet == 'Sheet'){
mySheet.activate();
} else {
mySheet = workSpreadsheet.insertSheet('Order Books', 1).activate();
}
var ui = SpreadsheetApp.getUi();
var string = 'https://api.binance.com/api/v3/depth?';
var symbolResponse = ui.prompt('Pair Name', 'Please enter the pair symbol.\n\nExamples: BTCUSDT or ETHBTC:', ui.ButtonSet.OK_CANCEL);
var symbolButton = symbolResponse.getSelectedButton();
if(symbolButton == ui.Button.CANCEL){return}
var mySymbol = symbolResponse.getResponseText();
mySymbol = mySymbol.toUpperCase();
string = string + "symbol=" + mySymbol;
var limitResponse = ui.prompt('Limit:', 'Please enter Limit (Period Quantity).\nValid limits are:5, 10, 20, 50, 100, 500, 1000. \n Default limit is 100.\n You can leave it blank and simply click OK.', ui.ButtonSet.OK_CANCEL);
if(limitResponse.getSelectedButton() == ui.Button.CANCEL){return}
var myLimit = Number(limitResponse.getResponseText());
if(myLimit != 5 && myLimit != 10 && myLimit != 20 && myLimit != 50 && myLimit != 100 && myLimit != 500 && myLimit != 1000){myLimit = 100;}
string = string + "&limit=" + myLimit;
var myDate = new Date().toUTCString();
var jsonOrderBookData = JSON.parse(UrlFetchApp.fetch('https://api.binance.com/api/v3/depth?symbol=' + mySymbol + '&limit=' + myLimit));
reporter(jsonOrderBookData);
} catch (e){
exceptionHandler(e)
}
}
The problem I have is to run UrlFetchApp.fetch again when it encounters an error. I need to run it several times to get the result. So, I need to prevent the script from stopping when an error (code -1003) occurs, but how can I do that?
EDIT: There is a function windows.onerror in javascript which can be set to prevent the program from stopping. Is it useable in GAS? if yes, how? if No, is there a similar solution for GAS?

Answer 1

You could call binanceOrderBook() from within your catch statement. E.g.
...
} catch (e){
binanceOrderBook()
exceptionHandler(e)
}
Of course you probably should have some condition that exits the function if a certain error occurs, or if you know that the function needs to run no more than x number of times you could check that it has run less than x times before executing. For example,
const maxValue = 10 // whatever the max number of executions should be
function binanceOrderBook(executions) {
if (executions >= maxValue) return;
try {
...
} catch(e) {
binanceOrderBook((executions || 0) + 1));
exceptionHandler(e); // note that I am including this here because it's in your original example, but as it is written now, exception handler won't be called until binanceOrderBook executes without an error.
}
}
[Edit] To answer your second question, there is no equivalent to window.onerror that I know of in GAS. However, window.onerror is a global event handler and so would affect errors thrown by any functions defined in your project. To address a concern with a single function call like this, you are better off using a try catch statement as you have.