Oversight is a library for observing method calls and property access.
var pointCount = 0;
var Point = function(x, y) {
this.x = x;
this.y = y;
};
Point = Oversight.observify(Point);
Oversight.before(Point, function(x, y) {
console.log('creating a point with coordinates x: ' + x + ', y: ' + y);
});
Oversight.after(Point, function(x, y) {
pointCount++;
console.log('finished creating a point, there are now ' + pointCount + ' points');
});
var p0 = new Point(1, 1);
var p1 = new Point(2, 2);
//output
//creating a point with coordinates x: 1, y: 1
//finished creating a point, there are now 1 points
//creating a point with coordinates x: 2, y: 2
//finished creating a point, there are now 2 points
There are a handful of observer types that can be applied to functions
aroundbeforeafterafterReturn
They will always execute in the above order. All observer functions are executed with the same arguments that the original function was invoked with, with the exception of afterReturn, which will take the return value of the original function as it's first parameter and the arguments of the original invocation as the remaining parameters.
before will execute before the original function with the same arguments.
var original = function(arg0, arg1) {
console.log('original', arg0, arg1);
};
original = Oversight.observify(original);
Oversight.before(original, function(arg0, arg1) {
console.log('before', arg0, arg1);
});
original('a', 'b');
//output
//before a b
//original a bafter will execute after the original function with the same arguments.
var original = function(arg0, arg1) {
console.log('original', arg0, arg1);
};
original = Oversight.observify(original);
Oversight.after(original, function(arg0, arg1) {
console.log('after', arg0, arg1);
});
original('a', 'b');
//output
//original a b
//after a bafterReturn will execute after the original function and after any after advice. It will be invoked with the first parameter set to the return value of the original function and the rest of the parameters set to the arguments to the original function.
var original = function(arg0, arg1) {
console.log('original', arg0, arg1);
return 'returnValue';
};
original = Oversight.observify(original);
Oversight.afterReturn(original, function(retn, arg0, arg1) {
console.log('afterReturn', retn, arg0, arg1);
});
original('a', 'b');
//output
//original a b
//afterReturn returnValue a bvia npm:
$ npm install oversightThere are three files in oversight/dist (after building), one for each of the common script loading methods:
oversight-amd.jsfor use with require.jsoversight-common.jsfor use with common js style modulesoversight-global.jsinjects Oversight into the global scope
Just take the one you like.
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