AppScript to strikethrough partial text on match

I believe your goal as follows.

• You want to reflect the strikethrough to the partial text in a cell using Google Apps Script as follows. (The sample image is from your question.)

  

In this case, I would like to propose to use RichTextValueBuilder. The sample script is as follows.

Sample script:

function myFunction() {
  const textsForStrikethrough = ["John"];  // Please set the texts you want to reflect the strikethrough.
  const sheetName = "Sheet1";  // Please set the sheet name.

  const sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheetName);
  const range = sheet.getDataRange();
  const modify = range.getValues().reduce((ar, e, r) => {
    e.forEach((f, c) => {
      textsForStrikethrough.forEach(g => {
        const idx = f.indexOf(g);
        if (idx > -1) ar.push({start: idx, end: idx + g.length, row: r, col: c});
      });
    });
    return ar;
  }, []);
  const textStyle = SpreadsheetApp.newTextStyle().setStrikethrough(true).build();
  const richTextValues = range.getRichTextValues();
  modify.forEach(({start, end, row, col}) => richTextValues[row][col] = richTextValues[row][col].copy().setTextStyle(start, end, textStyle).build());
  range.setRichTextValues(richTextValues);
}

Result:

When above script is run, the following results are obtained.

This is the sample input situation before the script is run.

In this case, const textsForStrikethrough = ["John"]; is used for the input situation.

In this case, const textsForStrikethrough = ["John", "Amy"]; is used for the input situation.

Note:

• In this sample script, all values are retrieved from the sheet and search the texts and reflect the strikethrough. So when you want to use this script to the specific range, please modify const range = sheet.getDataRange(); for your situation.
  • For example, from your sample image, when you want to use this script to the column "B", please modify it to const range = sheet.getRange("B1:B" + sheet.getLastRow());.

References:

• Class RichTextValue
• Class RichTextValueBuilder

Added:

About your following 2nd question,

This is perfect! Only other request I have, is how would we modify it to where it is referencing a series of other cells to lookup the names? The list of names changes daily, so looking to have all inputs be able to update by a simple change of the names on the sheet rather than modifying the code. So say the names could be input in cell A10:A15. Pulling that list of names and updating the "textsForStrikethrough" logic.

in this case, I think that at first, how about retrieving the values of cells "A10:A15", and use them as textsForStrikethrough?

Sample script 2:

function myFunction2() {
  // const textsForStrikethrough = ["John"];  // Please set the texts you want to reflect the strikethrough.
  const sheetName = "Sheet1";  // Please set the sheet name.

  const sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(sheetName);
  const range = sheet.getDataRange();
  
  const textsForStrikethrough = sheet.getRange("A10:A15").getValues().flat(); // Added
  
  const modify = range.getValues().reduce((ar, e, r) => {
    e.forEach((f, c) => {
      textsForStrikethrough.forEach(g => {
        const idx = f.indexOf(g);
        if (idx > -1) ar.push({start: idx, end: idx + g.length, row: r, col: c});
      });
    });
    return ar;
  }, []);
  const textStyle = SpreadsheetApp.newTextStyle().setStrikethrough(true).build();
  const richTextValues = range.getRichTextValues();
  modify.forEach(({start, end, row, col}) => richTextValues[row][col] = richTextValues[row][col].copy().setTextStyle(start, end, textStyle).build());
  range.setRichTextValues(richTextValues);
}

• In this script, the values of cells "A10:A15" in the sheet of sheetName are used as textsForStrikethrough.

Note:

• Unfortunately, I cannot understand about your actual situation. So when above script cannot be used for your actual situation, can you provide your sample Spreadsheet for replicating the issue? By this, I would like to confirm it.