Class TextValidation

// Add a text item to a form and require it to be a number within a range.
const form = FormApp.create('My form');
const textItem =
    form.addTextItem().setTitle('Pick a number between 1 and 100?');
const textValidation =
    FormApp.createTextValidation()
        .setHelpText('Input was not a number between 1 and 100.')
        .requireNumberBetween(1, 100)
        .build();
textItem.setValidation(textValidation);