node.js is it save to replace process.env object?

Question

Say I have extend function that

extend(obj1, obj2) -> creates new object does not mutate sources

According to documentation process.env is just an object, but I wonder is it save operation to do the followng:

process.env = extend(process.env, {MY_SETTING: 'Something'})

so process.env will be completely replaced new object with the same properties?

Answer 1

It's probably safe, but there is no good reason to do it. env is defined in C++ code ( https://github.com/joyent/node/blob/v0.10.28-release/src/node.cc#L2324-L2332 ). As you can see accessing each property actually involves getenv invocation, which has O(n) complexity, so enumeration and copying of whole env object would be quite inefficient.