Javascript AOP libraries [closed]

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Which Javascript AOP library do you use, and what are its key features ?

Answer 1

Here is what I found until now :

• dotvoid's implementation, clean syntax, nice to use, the article is a good introduction on why/how to use the given code, supports introductions, but is bugged,
• Dojo has what seems to be a good built-in implementation in dojox, here is a nice introduction on how to use it,
• there is a plugin for jQuery, jquery-aop, with a rougher syntax, passing objects and methods in a javascript object,
• AspectJS with an even rougher syntax (need to pass type of pointcut as arguments to a single method)

Like I said, dotvoid's code did not work. I corrected a little and got something that seems to work better :

InvalidAspect = new Error("Missing a valid aspect. Aspect is not a function.");
InvalidObject = new Error("Missing valid object or an array of valid objects.");
InvalidMethod = new Error("Missing valid method to apply aspect on.");
function doBefore(beforeFunc,func){
 return function(){
 beforeFunc.apply(this,arguments);
 return func.apply(this,arguments);
 }; 
}
function doAfter(func, afterFunc){
 return function(){
 var res = func.apply(this,arguments);
 afterFunc.apply(this,arguments);
 return res; 
 };
}
Aspects = function(){};
Aspects.prototype={
 _addIntroduction : function(intro, obj){
 for (var m in intro.prototype) {
 obj.prototype[m] = intro.prototype[m];
 }
 },
 addIntroduction : function(aspect, objs){
 var oType = typeof(objs);
 if (typeof(aspect) != 'function')
 throw(InvalidAspect);
 if (oType == 'function'){
 this._addIntroduction(aspect, objs);
 }
 else if (oType == 'object'){
 for (var n = 0; n < objs.length; n++){
 this._addIntroduction(aspect, objs[n]);
 }
 }
 else{
 throw InvalidObject;
 }
 },
 addBefore : function(aspect, obj, funcs){
 var fType = typeof(funcs);
 if (typeof(aspect) != 'function')
 throw(InvalidAspect);
 if (fType != 'object')
 funcs = Array(funcs);
 for (var n = 0; n < funcs.length; n++){
 var fName = funcs[n];
 var old = obj.prototype[fName];
 if (!old)
 throw InvalidMethod;
 var res = doBefore(aspect,old)
 obj.prototype[fName] = res;
 }
 },
 addAfter : function(aspect, obj, funcs) {
 if (typeof(aspect) != 'function')
 throw InvalidAspect;
 if (typeof(funcs) != 'object')
 funcs = Array(funcs);
 for (var n = 0; n < funcs.length; n++)
 {
 var fName = funcs[n];
 var old = obj.prototype[fName];
 if (!old)
 throw InvalidMethod;
 var res = doAfter(old,aspect);
 obj.prototype[fName] = res;
 }
 },
 addAround : function(aspect, obj, funcs){
 if (typeof(aspect) != 'function')
 throw InvalidAspect;
 if (typeof(funcs) != 'object')
 funcs = Array(funcs);
 for (var n = 0; n < funcs.length; n++)
 {
 var fName = funcs[n];
 var old = obj.prototype[fName];
 if (!old)
 throw InvalidMethod;
 var res = aspect(old);
 obj.prototype[fName] = res;
 }
 return true;
 }
}

• Heinrich Ulbricht: Does the code somehow work in Internet Explorer? As my tests failed, I googled around and it seems that IE doesn't have a "prototype"-property...
• glmxndr: I've been running tests on this on IE7. Works fine. Lower versions untested though.
• Konstantin Krass: 2014: I found this still very active framework jsAspect it seems to do what a AOP should do!

Answer 2

Have you seen meld.js and aop.js from https://github.com/cujojs?

SpringSource provides AOP functionality there, in addition to a bunch of other useful things for advanced Javascript programmers.

Disclaimer: I work for SpringSource.

• glmxndr: It's quite an old question... but thanks for the addition.

Answer 3

Based on dotvoid solution, I created my own version of JS AOP for my own projects needs. I basically want to minimize the aspect setup costs, so I added aspect setup functionality at Function.prototype.

Function.prototype.applyBefore = function (aspect, targetFuncNames) {
....
}

I also need to support aync callbacks, such as supporting authentication and authorization for certain methods. For example:

var authenticateAspect = function (error, success, context, args) {
 logger.log('authenticate (applyBefore async) aspect is being called');
 var request = $.ajax({
 url: "http://localhost/BlogWeb/api/user/authenticate",
 type: "GET",
 data: { username:'jeff', pwd:'jeff' },
 success: function (data) {
 if (data) {
 success();
 } else {
 error();
 }
 },
 error: error
 });
 return request;
};
Person.applyBefore(authenticateAspect, 'sendNotification');
var p1 = new Person();
p1.sendNotification();

To implement this, I need to run the security and and continue upon success or stop execution on failure.

var invalidAspect = new Error("Missing a valid aspect. Aspect is not a function."),
 invalidMethod = new Error("Missing valid method to apply aspect on.");
///Parameters: aspect - defines the methods we want call before or/and 
/// after each method call ob target obejct
/// targetFuncNames - target function names to apply aspects
///Return: it should return a new object with all aspects setup on target object
Function.prototype.applyBefore = function (aspect, targetFuncNames) {
 if (typeof (aspect) != 'function')
 throw invalidAspect;
 if (typeof (targetFuncNames) != 'object')
 targetFuncNames = Array(targetFuncNames);
 var targetObj = this;
 //error handling function
 // Copy the properties over onto the new prototype
 for (var i = 0, len = targetFuncNames.length; i < len; i++) {
 var funcName = targetFuncNames[i];
 var targetFunc = targetObj.prototype[funcName];
 if (!targetFunc)
 throw invalidMethod;
 targetObj.prototype[funcName] = function () {
 var self = this, args = arguments;
 var success = function() {
 return targetFunc.apply(self, args);
 };
 var error = function () {
 logger.log('applyBefore aspect failed to pass');
 //log the error and throw new error
 throw new Error('applyBefore aspect failed to pass');
 };
 var aspectResult = aspect.apply(null, Array.prototype.concat([error, success, self], args));
 return aspectResult;
 };
 }
};

Full implementation can be found at http://www.jeffjin.net/aop-with-javascript

• Peter Seliger: This implementation is as far away from AOP as can be, because it does not provide any abstraction to both, neither Joinpoint nor Aspect. With a more close look it does not even qualify for a basic before method-modifier. Its first argument is expected to be a function, but again referred wrongly to as aspect, even though, in terms of AOP, it might relate closely to an advice handler.