Created
February 10, 2012 19:24
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function handlerMaker(obj) { | |
return { | |
getOwnPropertyDescriptor: function(name) { | |
var desc = Object.getOwnPropertyDescriptor(obj, name); | |
// a trapping proxy's properties must always be configurable | |
if (desc !== undefined) { desc.configurable = true; } | |
return desc; | |
}, | |
getPropertyDescriptor: function(name) { | |
var desc = Object.getPropertyDescriptor(obj, name); // not in ES5 | |
// a trapping proxy's properties must always be configurable | |
if (desc !== undefined) { desc.configurable = true; } | |
return desc; | |
}, | |
getOwnPropertyNames: function() { | |
return Object.getOwnPropertyNames(obj); | |
}, | |
getPropertyNames: function() { | |
return Object.getPropertyNames(obj); // not in ES5 | |
}, | |
defineProperty: function(name, desc) { | |
Object.defineProperty(obj, name, desc); | |
}, | |
delete: function(name) { return delete obj[name]; }, | |
fix: function() { | |
if (Object.isFrozen(obj)) { | |
var result = {}; | |
Object.getOwnPropertyNames(obj).forEach(function(name) { | |
result[name] = Object.getOwnPropertyDescriptor(obj, name); | |
}); | |
return result; | |
} | |
// As long as obj is not frozen, the proxy won't allow itself to be fixed | |
return undefined; // will cause a TypeError to be thrown | |
}, | |
has: function(name) { return name in obj; }, | |
hasOwn: function(name) { return ({}).hasOwnProperty.call(obj, name); }, | |
get: function(receiver, name) { return obj[name]; }, | |
set: function(receiver, name, val) { obj[name] = val; return true; }, // bad behavior when set fails in non-strict mode | |
enumerate: function() { | |
var result = []; | |
for (var name in obj) { result.push(name); }; | |
return result; | |
}, | |
keys: function() { return Object.keys(obj); } | |
}; | |
} | |
var proxy = Proxy.create(handlerMaker(obj)); |
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