How can i use moment in a formatter?

[mok-liee]

Hello Team,

can u help me please. How can i use moment in a formatter?

const Parser = require("binary-parser").Parser;
const moment = require('moment');

let time = function(timestamp) {
	return moment(timestamp, 'YYMMDDHHmmssSS').format('YYYY-MM-DD HH:mm:ss.SS');
};

let Telegram = new Parser()
	.string('timestamp', {encoding: 'hex', length: 7, formatter: time});

The Exception is:

evalmachine.<anonymous>:9
        return moment(timestamp, 'YYMMDDHHmmssSS').format('YYYY-MM-DD HH:mm:ss.SS');
        ^

ReferenceError: moment is not defined
    at Parser.<anonymous> (evalmachine.<anonymous>:9:2)
...

I think the Problem is that Parser dont know moment. But how can i realize that?

[ElbowBaggins]

I know this is probably too late for you, but hopefully it helps someone.

When Parser invokes your formatter, it does so with Function.prototype.apply() and passes itself as the this argument. As a result, the function is now running in the context of the Parser and not the lexical context that you are expecting.

I addressed this by adding a $imports property to Parser.prototype where one could add anything they'd like to make available from within the Parser's context. Basically, using the above example, you want something like this.

const Parser = require('binary-parser').Parser;
const moment = require('moment');
Parser.prototype.$imports = {
    moment: moment
};

let time = function(timestamp) {
    return this.$imports.moment(timestamp, 'YYMMDDHHmmssSS').format('YYYY-MM-DD HH:mm:ss.SS');
};

let Telegram = new Parser().string('timestamp', { encoding: 'hex', length: 7, formatter: time });

You can use this approach to inject pretty much whatever you want in there.

[p0358]

Here's what appears to be possible, if you want to add a property to specific Parser object, and not a global:

let opts = parser.encoderOpts;
opts.test = "test";
parser.encoderSetOptions(opts);

parser = parser.array(name, {
    /* ... */
    formatter: item => this.encoderOpts.test
});

(this would replace all objects there to "test", but it shows that it's indeed accessible this way)
[you might also be interested in related comment in #33]

[p0358]

NVM, it still appears to be global for the whole parser. Fuck me...