JS client: Support for default parameter values

[delenius]

This is a feature request to support default parameter values in the generated JS client. These seem to be ignored currently.

[wing328]

For other API clients, we don't implement default value for parameters because the default value should be handled/added in the server side.

For your case, if the default value is not provided, will the server handle it properly?

[delenius]

I see, but then the problem is that the client will get confused about the arguments. For example, if I have one operation foo that takes one parameter bar (say as a query param), which has a default value, then the generated client API function will be

self.foo = function(bar, callback) {
...
}

Now, if the user just calls foo(myCallback), things will not work. You would have to at least call it with foo(null, myCallback) (which is kind of ugly).

However, I realize now that there will be problems when you have a mix of default and non-default parameters. E.g. this would not work:

self.foo = function(p1, p2 = true, p3, p4 = false){
 ...
}

I guess this is why the other JS client uses named parameters, like

foo({ p1: 17, p3: 1, p4: true })

(this would result in the server using the default for p2 since it is not passed, whereas p4 overrides its default).

[wing328]

Definitely valid point and we'll evaluate your suggestion using named parameter (which is already supported by C#, Ruby, etc)

[xhh]

We can implement optional parameters like in Ruby client. I'll submit a PR for it.

[wing328]

@delenius what's your view on using Ruby's style optional parameter in JS functions?

[delenius]

I like it, and I have seen that style used in JS libraries before.