If you want to implement different types of file with different extension then use the below code

function validateFile(file: File): boolean {
const allowedTypes: string[] = [‘image/jpeg’, ‘image/png’, ‘application/pdf’, ‘text/txt’];
const maxSize = 5 * 1024 * 1024; // Maximum file size (5MB)

    let isValidType = false;
    for (const type of allowedTypes) {
        if (file.type === type) {
            isValidType = true;
            break;
        }
    }

    if (!isValidType) {
        alert('Invalid file type. Only Text, JPEG, PNG, and PDF files are allowed.');
        return false;
    }

    if (file.size > maxSize) {
        alert('File size exceeds the maximum limit of 5MB.');
        return false;
    }

    return true;
}