Leaflet.org

Form validation has always been my least favorite part of web development. You need to duplicate validation on both client and server sides, handle loads of events, and worry about form element styling. To aid form validation, the HTML spec added some new form attributes like required and pattern to act as very basic validation. Did you know, however, that you can control native form validation using JavaScript? validity Each form element (input, for example) provides a validity property which represents a ValidityState. ValidityState looks something like this: // input.validity { badInput: false, customError: true, patternMismatch: false, rangeOverflow: false, rangeUnderflow: false,... more →