Small module with a couple helper methods related to VWE functionality. Based on http://blog.kenteken.tv/2011/05/06/code-snippets-formatteren-rdw-kenteken/

vwe_helpers.js

/**
 * Small module with a couple helper methods related to VWE functionality
 * Based on http://blog.kenteken.tv/2011/05/06/code-snippets-formatteren-rdw-kenteken/
 * 
 * @author Boye Oomens <[email protected]>
 * @type {Object}
 */
var vwe = {

	/**
	 * Possible plate number combinations (diplomat plates not included)
	 * @type {Array}
	 */
	combos: [
		/^[a-zA-Z]{2}[\d]{2}[\d]{2}$/, // 0 XX-99-99
		/^[\d]{2}[\d]{2}[a-zA-Z]{2}$/, // 1 99-99-XX
		/^[\d]{2}[a-zA-Z]{2}[\d]{2}$/, // 2 99-XX-99
		/^[a-zA-Z]{2}[\d]{2}[a-zA-Z]{2}$/, // 3 XX-99-XX
		/^[a-zA-Z]{2}[a-zA-Z]{2}[\d]{2}$/, // 4 XX-XX-99
		/^[\d]{2}[a-zA-Z]{2}[a-zA-Z]{2}$/, // 5 99-XX-XX
		/^[\d]{2}[a-zA-Z]{3}[\d]{1}$/, // 6 99-XXX-9
		/^[\d]{1}[a-zA-Z]{3}[\d]{2}$/, // 7 9-XXX-99
		/^[a-zA-Z]{2}[\d]{3}[a-zA-Z]{1}$/, // 8 XX-999-X
		/^[a-zA-Z]{1}[\d]{3}[a-zA-Z]{2}$/ // 9 X-999-XX
	],

	/**
	 * Formats the given license plate number
	 * 
	 * @param  {String} plateNr
	 * @return {Number|Boolean}
	 */
	format: function (plateNr, sideCode) {
		plateNr = plateNr.replace(/-/g, '').toUpperCase();

		if ( sideCode >= 6 ) {
			return plateNr.substr(0, 2) + '-' + plateNr.substr(2, 2) + '-' + plateNr.substr(4, 2);
		}

		if ( sideCode == 7 || sideCode == 9 ) {
			return plateNr.substr(0, 2) + '-' + plateNr.substr(2, 3) + '-' + plateNr.substr(5, 1);
		}

		if ( sideCode == 8 || sideCode == 10 ) {
			return plateNr.substr(0, 1) + '-' + plateNr.substr(1, 3) + '-' + plateNr.substr(4, 2);
		}

		return plateNr;
	},

	/**
	 * Fetches the sidecode of the given license plate number
	 * 
	 * @param  {String} plateNr
	 * @return {Number|Boolean}
	 */
	getSideCode: function (plateNr) {
		var combos = this.combos,
			i = combos.length;

		if ( !plateNr ) {
			return false;
		}

		while (i--) {
			if ( plateNr.match( combos[i] ) ) {
				return i + 1;
			}
		}
	},

	/**
	 * Checks whether the given license plate is valid (according to Dutch legislation)
	 * 
	 * @param  {String} plateNr
	 * @return {Boolean} 
	 */
	isValid: function (plateNr) {	
		var results = [],
			combos = this.combos,
			i = combos.length;

		if ( !plateNr ) {
			return false;
		}

		while (i--) {
			if ( combos[i].test( plateNr.replace(/-/g, '') ) ) {
				results.push( plateNr );
			}
		}

		return !!results.length;
	}
};