This is a simple captcha implementation.
Usage:
Initialize the captcha engine
const s = SimpleCaptchaEngine(numberOfCharacters, backGroundColor, charactersToUse, fontList)
Get image data url (which can be embedded into any image component)
imageUrl = s.getImageUrlData()
imageUrl = s.getImageUrlData(true) //Add strokes to image
Validate user input
s.validateCaptcha(string) //compare user input to captcha image