How to perform a transform on npm module using browserify

Question

By default, browserify does not perform transforms on modules included from node_modules, i.e. with no path.

I made a quick github repo that illustrates it here. The index.js file that gets browserified looks like this:

var fs = require('fs');
var testmodule = require('testmodule');
var trg1 = document.getElementById("target1");
var trg2 = document.getElementById("target2");
trg1.innerHTML = fs.readFileSync(__dirname+"/something.txt");
trg2.innerHTML = testmodule();

testmodule looks like this:

var fs = require('fs');
exports = module.exports = function() {
    return fs.readFileSync(__dirname+'/data.txt');
}

Using the brfs transform module, I want to be able to inline both calls to fs.readFileSync, but when I run browserify index.js -t brfs -o bundle.js, only the call in my main project gets inlined. Here is the bundle.js result:

;(function(e,t,n){function r(n,i){if(!t[n]){if(!e[n]){var s=typeof require=="function"&&require;if(!i&&s)return s(n,!0);throw new Error("Cannot find module '"+n+"'")}var o=t[n]={exports:{}};e[n][0](function(t){var i=e[n][1][t];return r(i?i:t)},o,o.exports)}return t[n].exports}for(var i=0;i<n.length;i++)r(n[i]);return r})({1:[function(require,module,exports){
// nothing to see here... no file methods for the browser

},{}],2:[function(require,module,exports){
var fs = require('fs');
var testmodule = require('testmodule');
var trg1 = document.getElementById("target1");
var trg2 = document.getElementById("target2");
trg1.innerHTML = "This is data from a file in the main project folder"; // TRANSFORMED
trg2.innerHTML = testmodule();
},{"fs":1,"testmodule":3}],3:[function(require,module,exports){
(function(__dirname){var fs = require('fs');
exports = module.exports = function() {
    return fs.readFileSync(__dirname+'/data.txt'); // NO TRANSFORM
}
})("/node_modules/testmodule")
},{"fs":1}]},{},[2])
;

Answer 1

Got some help from substack (author of browserify) on this one. To specify if a module outside of a project requires transformations, you need to specify a browserify.transform array in your package.json. So for the example I gave above, the package.json file in the testmodule directory looks like this:

{
    "name":"testmodule",
    "version":"0.0.0",
    "browserify": {
        "transform": ["brfs"]
    },
    "main": "index.js"
}