Question: Python's get method for dictionaries lets me specify what should be returned if a key doesn't exist. For my current case I want a dictionary returned. How do I do this in Javascript?

Answer: 
With modern javascript you can use the [nullish coalescing operator `??`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator)

```
const result = obj[key] ?? default;

```

This will return the default value if `key` doesn't exist in `obj`. It will also return the default in cases like `{myKey: undefined}` or `{myKey: null}`, which may or may not be the desired behavior.
this works for me

```
let obj = {"a": 1};
let default = 100
obj["a"] || default; // -> 1
obj["b"] || default; // -> 100

```

But! there are some limitation, if `!!obj["a"] === false` we always get default value... so it's better to just check if key in obj, to be completely sure.