string.toNumberString.js

if (!String.prototype.toNumberString) {
	/**
	 * Converts each character into its numerical representation of given base
	 * By default converts to Hexadecimal (base = 16)
	 * This conversion is required for JWT implementation http://kjur.github.io/jsrsasign/
	 * 
	 * Examples:
	 *   '*123'.toNumberString(); //returns '2a313233'
	 *   '*123'.toNumberString(10); //returns '42495051'
	 *   '*123'.toNumberString(8);  //returns '52616263';
	 *   '*123'.toNumberString(16, 1, 2, 'Hex:');  //returns 'Hex:3132';
	 */
	String.prototype.toNumberString = function(base, start, length, prefix) {
		start = start || 0;
		length = start + (undefined === length ? this.length : length);
		prefix = prefix || '';
		for (; start < length; start++) {
			prefix += this.charCodeAt(start).toString(base || 16);
		}
		return prefix;
	}
}