ES6: “import * as alias” vs “import alias”

From your example:

Case A:

//utils.js
export function doSomething()
{
//...
}

Case B:

//utils.js
export function doSomething()
{
//...
}
export default function doSomethingDefault()
{
//...
}

Result:

import utils from 'utils'
utils() // (Case A: undefined, Case B: doSomethingDefault)

import * as utils from 'utils'
utils // (Case A: utils = { doSomething: function }, Case B: utils = { doSomething: function, default: function })

import { doSomething } from 'utils'
doSomething() // (both Case A and Case B: doSomething = doSomething)

The difference between Case A and Case B is that, in Case A import utils from 'utils', utils will be undefined because there is no default export. In case B, utils will refer to doSomethingDefault.

With import * as utils from 'utils', in Case A utils will have one method (doSomething), while in Case B utils will have two methods (doSomething and default).