esrever.js

/*! https://mths.be/esrever v0.2.0 by @mathias */
;(function(root) {

	// Detect free variables `exports`
	var freeExports = typeof exports == 'object' && exports;

	// Detect free variable `module`
	var freeModule = typeof module == 'object' && module &&
		module.exports == freeExports && module;

	// Detect free variable `global`, from Node.js or Browserified code,
	// and use it as `root`
	var freeGlobal = typeof global == 'object' && global;
	if (freeGlobal.global === freeGlobal || freeGlobal.window === freeGlobal) {
		root = freeGlobal;
	}

	/*--------------------------------------------------------------------------*/

	var regexSymbolWithCombiningMarks = /([\0-\u02FF\u0370-\u1AAF\u1B00-\u1DBF\u1E00-\u20CF\u2100-\uD7FF\uE000-\uFE1F\uFE30-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?:[^\uD800-\uDBFF]|^)[\uDC00-\uDFFF])([\u0300-\u036F\u1AB0-\u1AFF\u1DC0-\u1DFF\u20D0-\u20FF\uFE20-\uFE2F]+)/g;
	var regexSurrogatePair = /([\uD800-\uDBFF])([\uDC00-\uDFFF])/g;

	var reverse = function(string) {
		// Step 1: deal with combining marks and astral symbols (surrogate pairs)
		string = string
			// Swap symbols with their combining marks so the combining marks go first
			.replace(regexSymbolWithCombiningMarks, function($0, $1, $2) {
				// Reverse the combining marks so they will end up in the same order
				// later on (after another round of reversing)
				return reverse($2) + $1;
			})
			// Swap high and low surrogates so the low surrogates go first
			.replace(regexSurrogatePair, '$2$1');
		// Step 2: reverse the code units in the string
		var result = '';
		var index = string.length;
		while (index--) {
			result += string.charAt(index);
		}
		return result;
	};

	/*--------------------------------------------------------------------------*/

	var esrever = {
		'version': '0.2.0',
		'reverse': reverse
	};

	// Some AMD build optimizers, like r.js, check for specific condition patterns
	// like the following:
	if (
		typeof define == 'function' &&
		typeof define.amd == 'object' &&
		define.amd
	) {
		define(function() {
			return esrever;
		});
	}	else if (freeExports && !freeExports.nodeType) {
		if (freeModule) { // in Node.js, io.js, or RingoJS v0.8.0+
			freeModule.exports = esrever;
		} else { // in Narwhal or RingoJS v0.7.0-
			for (var key in esrever) {
				esrever.hasOwnProperty(key) && (freeExports[key] = esrever[key]);
			}
		}
	} else { // in Rhino or a web browser
		root.esrever = esrever;
	}

}(this));