node.js / ES6 / class creation : SyntaxError: Unexpected reserved word

Question

I try to create a class on my node.js / express app.

It works in basic js / prototype mode such as :

function MyClass() { 
    /* constructor code *         


        

Answer 1

You need a newer version of nodejs. The class keyword is supported in 4.4.x, but I'm personally seeing it work in v4.2.6. (Not entirely sure what version of v8 released it, which is what would tell the node version.)

Answer 2

You can do this with io.js

iojs --use_strict --harmony_classes my-app.js

Or on node.js with traceur

var traceur = require('traceur');
traceur.require.makeDefault(function(file) {
  return file.indexOf('node_modules') == -1;
});

require('./my-app').run();

Make sure to test the new features before using them, some are not supported. Edit: You can check the compatibility list from here

Answer 3

I had this problem.

It was caused because I downloaded nodejs' source code than built/ compiled it on my Ubuntu. ./configure then make and make install.

For some reason the ES6 reserved words like class and extends were throwing SyntaxError: Unexpected reserved word, even when using --harmony flag.

It was solved by me downloading the nodejs binaries for linux (https://nodejs.org/download/).

Now class and extends work even without --harmony flag.

I believe the issue came about from my building/ compiling process. For some reason the ES6 additions were not built or configured properly.

The binaries, to my understanding, are built completely and correctly for linux already and therefore the ES6 is added and configured correctly.