function that uses regular expressions to split the email address at logical breakpoints (i.e., before a . or after a @). It then creates a string with HTML line breaks (<br>) where the email was split. This function assumes a maximum line length of 40 characters, which is typical for point-of-sale receipt printers.:

formatEmailForReceipt

// The standard width of a typical receipt paper is 80mm, print density is about 40-48 characters per line depending on font size.
// function that uses regular expressions to split the email address at logical breakpoints (i.e., before a . or after a @, etc.). 
// It then creates a string with HTML line breaks (<br>) where the email was split. This function assumes a maximum line length of 40 characters, which is typical for point-of-sale receipt printers.:

function formatEmailForReceipt(email: string): string {
    const MAX_LINE_LENGTH: number = 40;
    const MIN_BREAKPOINT_LENGTH: number = 10;  // The minimum length before a breakpoint to consider breaking
    let lines: string[] = [];
    let currentLine: string = "";

    // Split email into parts at breakpoints (@, ., -, _)
    const parts: string[] = email.split(/(?=@)|(?=(\.))|(?<=(-))|(?<=(_))/g);

    parts.forEach(part => {
        if (currentLine.length + part.length <= MAX_LINE_LENGTH) {
            currentLine += part;
        } else if (currentLine.length >= MIN_BREAKPOINT_LENGTH) {
            lines.push(currentLine);
            currentLine = part;
        } else {
            currentLine += part;
        }
    });

    lines.push(currentLine);

    return lines.join("<br>");
}