Const urlRegexp
urlRegexp: RegExp = new RegExp('^(https?:\\/\\/)?' + // protocol'((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|' + // domain name'((\\d{1,3}\\.){3}\\d{1,3}))' + // OR ip (v4) address'(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*' + // port and path'(\\?[;&a-z\\d%_.~+=-]*)?' + // query string'(\\#[-a-z\\d_]*)?$', 'i')