calculate range of values entered by user Custom function Google Appscript - regex

Question

I want to use arrayformula for my custom function if possible because I want to input a range of values
I also get this error: TypeError: Cannot read property "0" from null.
Also, this: Service invoked too many times in a short time: exec qps. Try Utilities.sleep(1000) between calls
var regExp = new RegExp("Item: ([^:]+)(?=\n)");
var matches=new regExp(input);
return matches[0];
}
Really appreciated some help
Edit:
Based on the second picture, I also try using this regex formula to find word start with "Billing address"
But for the first picture, I used regex formula to find word start with "Item"
The error appears the same for both custom function.

Answer 1

If you want to use a custom function which finds all the strings that start with Item or item and extracts the contents from after the finding, you can use the code provided below. The regular expression is checked by using the match() function and returns the desired result; otherwise, it will return null.
function ITEM(input) {
var regEx = /(?:I|i)tem\s*(.*)$/;
var matches = input.match(regEx);
if (matches && matches.length > 1) {
return matches[1];
} else {
return null;
}
}
If you want to use the RegExp like you did in the code you have shared, you should use \\ instead of \.
For checking and verifying the regular expressions you can use this site.
The Service invoked too many times in a short time: exec qps. Try Utilities.sleep(1000) between calls. error message you are getting is due to the fact that you are trying to call the custom function on too many cells - for example dragging the custom function on too many cells at once. You can check more about this error message here.