Parameter names with ES6?

Question

I have defined a function like:

function call_api(url, callback, query = {}, body = {}) 

I expected a syntax where I can provide body and skip query:

call_api('/api/clients/new', function(x){console.log(x)}, body={1:2}) 

But I have to use this workaround:

call_api('/api/clients/new', function(x){console.log(x)}, {}, {1:2}) 

Even if I provide body=, it appears its appearing as the query parameter. I use Babel with Webpack. I tried the syntax in Chrome console and in Webpack source.

Is such a syntax supported by ES6? How does it work?

Answer 1

I recommend that you work around this with passing an object and using destructuring for objects:

function callApi({url, callback, query = {}, body = {}}) 

And then call it as:

callAPI({url: "/api/..", callback: (x => console.log(x)), body: {a:2}}) 

Which would give you syntax similar to the one you want.

Named arguments have been considered and rejected for JavaScript, unlike other languages like C# and Python which sport them. Here is a recent discussion about it from the language mailing list.

Answer 2

As shown on this site, the defaults are just for parameters that need a default value (like an options parameter), but not for 'skipping' parameters.

What you're trying to do is

// function definition function hi(a,b,c,d)  // function call hi(a,b,d) 

ES6 is still going to think that your 'd', is the defined c, regardless of your default value.
So no, ES6 does not have such syntax.