Complete validate function and auto detectand prevent error

[JohnAdib]

Hi and thanks for lib;) Some tips to improve

• it's better to automatically detect format of barcode
• complete validate function to return format
• prevent error in code if string of code is not valid on selected format

[SanichKotikov]

Hi,

it's better to automatically detect format of barcode complete validate function to return format

https://github.com/lindell/JsBarcode/issues/186#issuecomment-325422746

prevent error in code if string of code is not valid on selected format

You can use valid option or try/catch to avoid it.