for in loops over enumerable property names of an object. for of (new in ES6) does use an object-specific iterator and loops over the values generated by that. In your example, the array iterator does yield all the values in the array (ignoring non-index properties).
bject does not have forEach, it belongs to Array prototype. If you want to iterate through each key-value pair in the object and take the values. You can do this: Usage note: For an object v = {“cat”:”large”, “dog”: “small”, “bird”: “tiny”};, Object.keys(v) gives you an array of the keys so you get [“cat”,”dog”,”bird”]
You forgot the .class: Note that this kind of code is usually the sign of a poor OO design. Also note that comparing the class of an object with a class and using instanceof is not the same thing. For example: is false, whereas is true. Whether one or the other must be used depends on … Read more
To get a fully independent copy of an object you can use the copy.deepcopy() function. For more details about shallow and deep copying please refer to the other answers to this question and the nice explanation in this answer to a related question.
Never ever extend Object.prototype. Horrible things will happen to your code. Things will break. You’re extending all object types, including object literals. Here’s a quick example you can try: Instead create a function that you pass the object.
By “undefined object as a parameter”, I assume you mean that you’re looking to write a function that doesn’t specify the type of the object in the function declaration, allowing you to only have one function. This can be done with generics. Instead of: you can have: Test: See Java generics for more information.
Why is cls sometimes used instead of self as an argument in Python classes? For example:
To remove a property from an object (mutating the object), you can do it like this: Demo For anyone interested in reading more about it, Stack Overflow user kangax has written an incredibly in-depth blog post about the delete statement on their blog, Understanding delete. It is highly recommended. If you’d like a new object with all the keys of the original … Read more
Native deep cloning It’s called “structured cloning”, works experimentally in Node 11 and later, and hopefully will land in browsers. See this answer for more details. Fast cloning with data loss – JSON.parse/stringify If you do not use Dates, functions, undefined, Infinity, RegExps, Maps, Sets, Blobs, FileLists, ImageDatas, sparse Arrays, Typed Arrays or other complex types within your object, a … Read more
Create a copy constructor: Every object has also a clone method which can be used to copy the object, but don’t use it. It’s way too easy to create a class and do improper clone method. If you are going to do that, read at least what Joshua Bloch has to say about it in Effective … Read more