CoffeeScript: assigning multiple properties to an initialised object

Question

w = {c: true}
w =
  a: 4
  b: true
console.log w

I expect the result w to be {a: 4, b: true, c: true}, but I get {a: 4, b: true}. How can I do multiple assignments to object properties without loosing already set properties?

The answers to [this question](http://stackoverflow.com/q/929776/306084) might prove useful, as what you're doing is merging properties in to the initial object. — pjmorse, Sep 17 '14 at 14:35

score 1 · Answer 1 · answered Sep 17 '14 at 14:46

1

CoffeeScript: assigning multiple properties to an initialised object has been the best answer so far.

But if you only want to add a few properties to an object you can just do:

w = {c: true}
w.a = 4
w['b'] = true  # alternative notation

Also, this question is more about JavaScript than CoffeeScript.

answered Sep 17 '14 at 14:46

Tomasz Zieliński

16,136
7
59
83

That's obviuous I know ... but not very pretty, I am looking for a short notation, in real life w is an object with a long name and I have many properties to add. – ronnydw Sep 17 '14 at 14:54

score 0 · Answer 2 · answered Sep 17 '14 at 14:28

0

I don't think it can be done directly. I believe, you need to iterate:

w = {c: true}
temp =
  a: 4
  b: true
w[k] = v for k,v of temp
console.log w

answered Sep 17 '14 at 14:28

Jakub Fedyczak

2,174
1
13
15

hmm... this does the assigment of each property twice – ronnydw Sep 17 '14 at 14:46
True, but solution from @Yuri does it same way - look at the transpiled code. – Jakub Fedyczak Sep 17 '14 at 14:50
Most efficient way seems to be from @Tomasz Zieliński - not very pretty though. – Jakub Fedyczak Sep 17 '14 at 14:51

score 0 · Answer 3 · answered Sep 17 '14 at 14:32

0

w = {c: true}
w[i] = v for i,v of {
  a: 4
  b: true
}
console.log w

answered Sep 17 '14 at 14:32

YuS

2,025
1
15
24

CoffeeScript: assigning multiple properties to an initialised object

3 Answers3