All current browsers have native JSON support built in. So as long as you’re not dealing with prehistoric browsers like IE6/7 you can do it just as easily as that: var j = { “name”: “binchen” }; console.log(JSON.stringify(j));
Unfortunately there is no perfect way, unless you use _proto_ recursively and access all non-enumerable properties, but this works in Firefox only. So the best I can do is to guess usage scenarios. 1) Fast and limited. Works when you have simple JSON-style objects without methods and DOM nodes inside: JSON.stringify(obj1) === JSON.stringify(obj2) The ORDER … Read more
In Python, the ‘null’ object is the singleton None. To check if something is None, use the is identity operator: if foo is None: …
Is there any reason for a class declaration to inherit from object? In Python 3, apart from compatibility between Python 2 and 3, no reason. In Python 2, many reasons. Python 2.x story: In Python 2.x (from 2.2 onwards) there’s two styles of classes depending on the presence or absence of object as a base-class: … Read more
Try the JavaScript in operator. if (‘key’ in myObj) And the inverse. if (!(‘key’ in myObj)) Be careful! The in operator matches all object keys, including those in the object’s prototype chain. Use myObj.hasOwnProperty(‘key’) to check an object’s own keys and will only return true if key is available on myObj directly: myObj.hasOwnProperty(‘key’) Unless you … Read more
Given a module foo with method bar: import foo bar = getattr(foo, ‘bar’) result = bar() getattr can similarly be used on class instance bound methods, module-level methods, class methods… the list goes on.
Iterating over properties requires this additional hasOwnProperty check: for (var prop in obj) { if (Object.prototype.hasOwnProperty.call(obj, prop)) { // do stuff } } It’s necessary because an object’s prototype contains additional properties for the object which are technically part of the object. These additional properties are inherited from the base object class, but are still … Read more
The usual way to check if the value of a property is the special value undefined, is: if(o.myProperty === undefined) { alert(“myProperty value is the special value `undefined`”); } To check if an object does not actually have such a property, and will therefore return undefined by default when you try to access it: if(!o.hasOwnProperty(‘myProperty’)) … Read more
Checking for undefined-ness is not an accurate way of testing whether a key exists. What if the key exists but the value is actually undefined? var obj = { key: undefined }; console.log(obj[“key”] !== undefined); // false, but the key exists! You should instead use the in operator: var obj = { key: undefined }; … Read more