wit.ai quickstart.js error from node, unexpected token{ - wit.ai

Question

I am going through the wit.ai quickstart tutorial and get an error from node (version 4.5.0 LTS), but I don't see the error in the code and also, it is the example code downloaded directly from wit.ai:
examples\quickstart.js:39
const {sessionId, context, entities} = request;
SyntaxError: Unexpected token {
at exports.runInThisContext (vm.js:53:16)
at Module._compile (module.js:373:25)
at Object.Module._extensions..js (module.js:416:10)
at Module.load (module.js:343:32)
at Function.Module._load (module.js:300:12)
at Function.Module.runMain (module.js:441:10)
at startup (node.js:139:18)
at node.js:974:3
Also, the code in the download from git is different than the code shown on the tutorial page:
Code from the git clone, example/quickstart.js is this:
'use strict';
let Wit = null;
let interactive = null;
try {
// if running from repo
Wit = require('../').Wit;
interactive = require('../').interactive;
} catch (e) {
Wit = require('node-wit').Wit;
interactive = require('node-wit').interactive;
}
const accessToken = (() => {
if (process.argv.length !== 3) {
console.log('usage: node examples/quickstart.js <wit-access-token>');
process.exit(1);
}
return process.argv[2];
})();
// Quickstart example
// See https://wit.ai/ar7hur/quickstart
const firstEntityValue = (entities, entity) => {
const val = entities && entities[entity] &&
Array.isArray(entities[entity]) &&
entities[entity].length > 0 &&
entities[entity][0].value
;
if (!val) {
return null;
}
return typeof val === 'object' ? val.value : val;
};
const actions = {
send(request, response) {
const {sessionId, context, entities} = request;
const {text, quickreplies} = response;
console.log('sending...', JSON.stringify(response));
},
getForecast({context, entities}) {
var location = firstEntityValue(entities, 'location');
if (location) {
context.forecast = 'sunny in ' + location; // we should call a weather API here
delete context.missingLocation;
} else {
context.missingLocation = true;
delete context.forecast;
}
return context;
},
};
const client = new Wit({accessToken, actions});
interactive(client);
but the tutorial says the const actions section should be this:
const actions = {
send(request, response) {
const {sessionId, context, entities} = request;
const {text, quickreplies} = response;
return new Promise(function(resolve, reject) {
console.log('sending...', JSON.stringify(response));
return resolve();
});
},
getForecast({context, entities}) {
return new Promise(function(resolve, reject) {
// Here should go the api call, e.g.:
// context.forecast = apiCall(context.loc)
context.forecast = 'sunny';
return resolve(context);
});
},
};
Regardless, both versions give the same error.

Answer 1

Turns out that, due to some ECMAScript 6 features in the code, if your node version <= 6.x.x, you have to add the flag harmony_destructuring to the node command line, as illustrated here:
node --harmony_destructuring examples/quickstart.js