export default should use const/let, not var.

[zbraniecki]

Currently, when exporting a default object, it assigns it using var which is unnecessary.

Example:

export default {
  foo: 1
};

rollup ./test.js

var test = {
  foo: 1
};

Instead, it should use const.

[eventualbuddha]

This should be opt-in, if such and option existed. Rollup is most commonly used as the final step in bundling JavaScript libraries, so using const would render the output dependent on ES2015 features.

[zbraniecki]

agree. I think we're at the point where we see projects that are targeting es6-compatible targets and rollup is used as a module bundler. I'd like to see this feature mostly for those scenarios so that using rollup doesn't mean regressing to es2015.

[nicolasparada]

Agree. Now I'm using:

const myModule = {
    foo: 'bar'
}

export default myModule

[Rich-Harris]

Have raised #684

[Rich-Harris]

As of 0.26.6, you can use preferConst: true to use const instead of var in these situations

[zbraniecki]

that works great! Thank you :)