Age:
55 40 20 19

Results:

    // Example 1:
    if (CustomerAge >= 55) {
        document.write("Dude - you're old!");
    }
    document.write("<br />Rest of the code...");
    
    // Example 2:
    if (CustomerAge >= 55) {
        document.write("Dude - you're old!");
    }
    else {
        document.write("You're not old.");
    }
    document.write("<br />Rest of the code...");
    
    // Example 3:
    if (CustomerAge >= 55) {
        document.write("Dude - you're old!");
    }
    else if (CustomerAge > 35) {
        document.write("You're middle age.");
    }
    else if (CustomerAge > 19) {
        document.write("You're young.");
    }
    document.write("<br />Rest of the code...");
    
    // Example 4:
    if (CustomerAge >= 55) {
        document.write("Dude - you're old!");
    }
    else if (CustomerAge > 35) {
        document.write("You're middle age.");
    }
    else if (CustomerAge > 19) {
        document.write("You're young.");
    }
    else {
        document.write("Dude - you're too young!");
    }
    document.write("<br />Rest of the code...");