Function parameter destructuring in Meteor for mailparser

wickedmuso · May 12, 2017, 11:42am

Has anyone been using the mailparser npm package in Meteor?

I need to use it (or something just as simple) but, while it supports both callback and promise, the promise implementation in the simpleParser function is using a strange function parameter destructuring syntax (which I believe works in Node 6) that will not compile in Meteor 1.4+.

The offending js file is only 90 lines long at this location:

github.com

nodemailer/mailparser/blob/master/lib/simple-parser.js

'use strict';

const MailParser = require('./mail-parser.js');

module.exports = (input, options, callback) => {
    if (!callback && typeof options === 'function') {
        callback = options;
        options = false;
    }

    let promise;
    if (!callback) {
        promise = new Promise((resolve, reject) => {
            callback = callbackPromise(resolve, reject);
        });
    }

    options = options || {};
    let keepCidLinks = !!options.keepCidLinks;

This file has been truncated. show original

However, it is the last 10 lines (as follows) where the issue is:

function callbackPromise(resolve, reject) {
    return function (...args) {
        let err = args.shift();
        if (err) {
            reject(err);
        } else {
            resolve(...args);
        }
    };
}

The …args syntax causes an error. I am not using the promise mechanism and so I can edit this out in my local code but, of course, a CI build pulls down the module fresh.

Aside from forking the repo, making a very tiny change, and either issuing a pull request (or just using the modified repo directly), my questions are:

is there an easier way to fix this (e.g. beta version of babel or such that might handle the syntax)?
Is there any code similar to mailparser that others would recommend?
does anyone know the timeline for Meteor to support Node 6?

[I’m looking for a quick solution as I have a looming deadline - the long solution would just be to fix it myself which is not possible at present due to time constraints]

Rgds

wickedmuso · June 19, 2017, 8:33pm

Further to the above…

I pulled the node module out of the node_modules folder with a view to just keeping a local copy of this and “fixing” whatever was broken.

Suddenly, the code started working without modification.

It seems as though when it is being loaded from node_modules that the transpiler does not recognise the syntax but it is fine when it is directly imported from a path in my own root directory.

So, for now, I have a “solution” whereby I have removed it as an NPM package and have just incorporated the code directly myself.

This is, indeed. strange.