proper way of using es6 classes in a nodejs project

Question

I'd like to be able to use the cool es6 classes feature of nodejs 4.1.2

I created the following project:

a.js:

class a {
  constructor(test) {
   a.test=test;
  }
}

index.js:

require('./a.js');
var b = new a(5);

as you can see I create a simple class that it's constructor gets a parameter. and in my include i require that class and create a new object based on that class. pretty simple.. but still i'm getting the following error:

SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
at exports.runInThisContext (vm.js:53:16)
at Module._compile (module.js:413:25)
at Object.Module._extensions..js (module.js:452:10)
at Module.load (module.js:355:32)
at Function.Module._load (module.js:310:12)
at Module.require (module.js:365:17)
at require (module.js:384:17)
at Object.<anonymous> (/Users/ufk/work-projects/bingo/server/bingo-tiny/index.js:1:63)
at Module._compile (module.js:434:26)
at Object.Module._extensions..js (module.js:452:10)

any ideas why ?

don't i need to enable strict mode? it's not enabled by default no ? — ufk
– ufk, Commented Oct 11, 2015 at 9:10
You need to enable strict mode, it's not (yet) enabled by default. — Madara's Ghost
– Madara's Ghost, Commented Oct 11, 2015 at 9:10
i added "use strict"; at the beginning of index.js but the results are the same — ufk
– ufk, Commented Oct 11, 2015 at 9:14

smirnov · Accepted Answer · 2015-10-20 18:56:17Z

36

Or you can run like this:

node --use_strict index.js

answered Oct 20, 2015 at 18:56

smirnov

4113 silver badges9 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Litty Over a year ago

Much better than putting "use strict" in the scripts. Also, the order of arguments seems to matter: node index.js --use_strict does not work.

Alasdair McLeay Over a year ago

Running your entire app in strict mode means you won't be able to use modules that assume you are not running in strict mode. You may find yourself doing a lot of refactoring down the line if you do this.

ufk · Accepted Answer · 2015-10-11 09:23:26Z

26

i'm still confused about why 'use strict' is needed, but this is the code that works:

index.js:

"use strict"; 
var a = require('./a.js');
var b = new a(5);

a.js:

"use strict";
class a {
 constructor(test) {
  a.test=test;
 } 
}
module.exports=a;

answered Oct 11, 2015 at 9:23

ufk

32.4k74 gold badges258 silver badges422 bronze badges

1 Comment

Felix Kling Over a year ago

"i'm still confused about why 'use strict' is needed" I think the error message is pretty clear, isn't it? "Block-scoped declarations (let, const, function, class) not yet supported outside strict mode" You need it because class is not yet supported outside of strict mode.

Collectives™ on Stack Overflow

proper way of using es6 classes in a nodejs project

2 Answers 2

2 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related