How to fix 'Function declarations should not be placed in blocks' error in Javascript es6?

Question

After a long time without using Javascript, I try to do understand what is es6, modules and iife.

So I make a little piece of code :

{
    'use strict';

    let version = '1.0.0';

    function init(){
        /* ... */
    }

    window.Test = {
        version: version,
        init: init
    };
}

And jshint returns this error : Function declarations should not be placed in blocks. Use a function expression or move the statement to the top of the outer function.

But, if I use the es5 format (function(){...}()) there is no problem. So what did I misunderstand ?

Furthermore, if someone have some time to answer some questions more :

'use strict' is necessary or redundant ?
I use an iife, but is it a module too ? (I think, I have very misunderstand this part)
window.Test is it the best way to export my variable Test ?

Thank you in advance for your answers, Sam.

EDIT : a good video to understand module : https://www.youtube.com/watch?v=qJWALEoGge4

What do you do with this code? Is it imported by something else, or does init() do everything you want to do? — apoteet, Jul 15 '19 at 17:29
Why is it not an IIFE ? I thought that was the case after seeing these sites : http://es6-features.org/#BlockScopedFunctions https://jack.ofspades.com/es6-iife-with-fat-arrow-functions/ — S.MyName, Jul 15 '19 at 18:28
I use it in a html page and the function init was just for the example, I have a LOT of functions to put in this script and I want to use it it like an API by using the Test variable. — S.MyName, Jul 15 '19 at 18:30

score 1 · Accepted Answer · answered Jul 15 '19 at 18:54

And jshint returns this error: Function declarations should not be placed in blocks. Use a function expression or move the statement to the top of the outer function.

That means that jshint doesn't understand ES6. Or you might need to configure it so that it does.

'use strict' is necessary or redundant?

The one you used here doesn't work, as directive prologues can only be placed in functions (or on the begin of a module or script), but not in a block.

I use an iife, but is it a module too?

No, you are not using an IIFE here. It's just a block, but that's ok.

It does implement the module pattern ("create an object with access to privately-scoped internals"), but it is not an ES6 module.

window.Test is it the best way to export my variable Test?

No, I would recommend declaring it with var.

I think, I understand now. Thanks. – S.MyName Jul 15 '19 at 22:30 — S.MyName, Jul 15 '19 at 22:30

How to fix 'Function declarations should not be placed in blocks' error in Javascript es6?

1 Answers1