Gracefully handle files that cannot be required

I have a file (settings.js) that is compiled by browserify. I want it to require a settings_local.js file only if if it exists. From the documentation and source code, I can’t figure out if this is possible. This is what I currently have:

var settings_local = {};
try {
  settings_local = require('./settings_local.js');
} catch (e) {
}

This is the error I get:

events.js:82
      throw er; // Unhandled 'error' event
            ^
Error: Cannot find module './settings_local.js' from '/opt/galaxy.js-mobile-gamepad/src/js'
    at /opt/galaxy.js-mobile-gamepad/node_modules/browserify/node_modules/resolve/lib/async.js:42:25
    at load (/opt/galaxy.js-mobile-gamepad/node_modules/browserify/node_modules/resolve/lib/async.js:60:43)
    at /opt/galaxy.js-mobile-gamepad/node_modules/browserify/node_modules/resolve/lib/async.js:66:22
    at /opt/galaxy.js-mobile-gamepad/node_modules/browserify/node_modules/resolve/lib/async.js:21:47
    at Object.oncomplete (fs.js:97:15)

[jscissr]

I have the same problem browserifying ws. It contains the following file:

try {
  module.exports = require('utf-8-validate');
} catch (e) {
  module.exports = require('./Validation.fallback');
}

I think it should be possible for browserify to detect requires inside a try/catch, and automatically exclude() it if it can’t be found (not ignore(), because then no error is thrown and you don’t get the fallback).

Do you think it’s possible? I would try to make a PR.

[hawkerboy7]

Hi, I have been running into this issue as well and I a different solution approach which I feel is relatively easy to make and does not break backwards compatibility. I may be quite wrong though 😃

I think making Browserify detect a require within a try catch block would be a bit hard to make whilst keep everything working the way you’d expect it to work and remain backwards compatible. Also the catch (e) block would now somehow contain a server side error, while the bundle file is only executed by the browser, so you’d need browserify to add some error object containing possible try catch errors (with stack) and send it to the client which may not be ideal for production-environments.

What it boils down to I believe is that we’d like to be able to make the browserify.bundle() function continue the bundling process instead of breaking when a file is required that does not exsist / is not found. However this is not always the case for every file. So instead of hardcoding the list of ‘silently-continue-if-not-found’ files server-side using the option ignoreMissing, perhaps the following could be added to the require function?

var settings = {a: 1, b: 2};
var item = require("./item");
var localSettings = require.dontBreakIfNotFound("./local-settings");
if (localSettings !== undefined) {
  settings = localSettings;
};

OR

var settings = {a: 1, b: 2};
var item = require("./item");
var localSettings = require("./local-settings", {ignoreMissing: true});
if (localSettings !== undefined) {
  settings = localSettings;
};

With this setup:

• if the file item.js is not found the bundle breaks (the way Browserify already works).
• if the file local-settings.js is not found the bundle would just return undefined (or null) but not break allowing you to optionally have the file local-settings.js.

Except for the terrible name dontBreakIfNotFound 😏 what do you think of either setup @jmm and @jscissr or does this already exists?