Apps Scirpt and regex. How? - regex

Question

I am using .indexOf() to parse an array in a separate sheet via url and find a string in a header to return a numerical value or -1. Issue is I need to find the string match that is non case sensitive. ie var targetEmail = targetHeader.indexOf("Email"); would need to match "email", "user email", User email", etc. Normally I would use a regex but can't find a way to do this in Apps Script. Please any help would be very much appreciated.
sample code below:
var userHeader = USER.getRange(1, 1, 1, USER.getLastColumn()).getValues()[0];
var targetHeader = importSheet.getRange(1, 1, 1, importSheet.getLastColumn()).getValues()[0];
var ui = SpreadsheetApp.getUi();
var targetEmail = targetHeader.indexOf("Email");
if(targetEmail == -1)
ui.alert("Can not find Email column. Please rename column in source sheet.");

Answer 1

Using Javascript RegExp, you can use the following
let targetEmail = targetHeader.findIndex(h => /email/gi.test(h));
if(targetEmail == -1)
ui.alert("Can not find Email column. Please rename column in source sheet.");
Note: findIndex, let and the function shorthand will only work if your script is using the new V8 runtime.
I personally prefer to name the column I want using Google Sheets named ranges, and then use getNamedRanges(), so I'll be able to find the column number by its range name, regardless of the column heading text. If columns are inserted or deleted, the named range still points to the column you're looking for.

Answer 2

You could solve for this by
(1) joining the array into a string
targetHeader.join()
(2) and then changing the string to lowercase
toLowerCase()
and then looking for "email" (lower case).
var targetHeader = importSheet.getRange(1, 1, 1, importSheet.getLastColumn()).getValues()[0];
targetHeader = targetHeader.join().toLowerCase();
var targetEmail = targetHeader.indexOf('email');
Edit:
To find the column number with the word 'email' in it:
var importSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Sheet101');
var targetHeader = importSheet.getRange(1, 1, 1, importSheet.getLastColumn()).getValues()[0];
var flag = false;
for (var c = 0; c < targetHeader.length; c++) {
var cellValue = targetHeader[c].toLowerCase();
if (cellValue.indexOf('email') > -1) {
flag = true;
break;
}
}
if (!flag) {
// ui alert that email not found
} else {
var columnWithEmalInHeader = c + 1;
// column with value 'email' found. Column number is c+1
// first time match of 'email' will pop-up here. All subsequent amounts will be ignored.
}