RegExp to validate a date format in JS, but needs extra checks for leap years and 30 day months

regexp-date-validation-collection.js

// date format: 'YYYY-MM-dd'
var RegExp = /^(199\\d)|([2-9]\\d{3})-(0?[1-9]|1[012])-(0?[1-9]|[12][0-9]|3[01])$/;
            
// date format:  'MM/dd/YYYY',
RegExp = /^(0[1-9]|1[0-2])\/(0[1-9]|1\d|2\d|3[01])\/(19|20)\d{2}$/;
// passed as a string
var regexp = new RegExp('^(0[1-9]|1[0-2])\/(0[1-9]|1\\d|2\\d|3[01])\/(19|20)\\d{2}$');