Cannot find ambient module declaration in .d.ts

When trying to transpile and bundle .ts file via Gulp/Browserify/Tsify the task fails with "Cannot find module" although standard tsc transpilation works.

I created an ambient module declaration based on TypeScript handbook:

// File: ./src/node_modules/mymodule.d.ts
declare module "mymodule"
{
    export class MyModule
    {
        public static Report(message:string):any;
    }
}

And I'm trying to import it in another file:

// File: ./src/consumer.ts
import {MyModule} from "mymodule";
MyModule.Report("MyModule was found by consumer");

The standard transpilation by TSC works ok: tsc ./src/consumer.ts

But when trying to transpile with the use of Browserify/Tsify/Gulp the gulp task fails:

// File: gulpfile.js
var gulp = require('gulp');
var browserify = require('browserify');
var source = require('vinyl-source-stream');
var tsify = require('tsify');

gulp.task('default', function () {
    return browserify({
        basedir: '.',
        debug: true,
        entries: ['src/consumer.ts'],
        cache: {},
        packageCache: {}
    })
    .plugin(tsify)
    .bundle()
    .pipe(source('consumer.js'))
    .pipe(gulp.dest('dist'));
});

The error is: Error: Cannot find module 'mymodule' from 'D:\Projects\Playground\TSTest\src'

I've put together a minimal repository which replicates the issue:
https://github.com/mnovotny/tsify-issue-250

Thanks for opening such a thorough issue. Unfortunately, I don't have the time, at the moment, to figure out why this isn't working for you, but I do have some suggestions:

Whentsc is run with file specified on the command line, it ignores any tsconfig.json file, so it might not be doing what you expect it do be doing.
Browserify needs to be able to resolve the modules and, AFAICT, ./src/node_modules/mymodule.d.ts is not a valid location for module resolution using Node's resolve algorithm. I would have though that it would have to be in a directory under node_modules. I guess it's possible that this is working - for some reason - with tsc but not for Browserify.
To obtain more diagnostic information, you can switch on the logging that's built into tsify - see the Debugging section in CONTRIBUTING.md. It might give you some hints as to what is going on.

Good luck.

Thanks for the reply. Here are my findings:

tsc compilation with tsconfig.json also works OK. I've tried putting consumer.ts to files[ ] and ran tsc with the -p option. It does produce a slightly different .js file but no error is thrown.
According to https://www.typescriptlang.org/docs/handbook/module-resolution.html#how-typescript-resolves-modules the location ./src/node_modules/mymodule.d.ts is a valid location. Anyway, I've tried copying the ambient declaration to ./node_modules/@types/mymodule/index.d.ts and Browserify/Tsify threw an error Duplicate identifier 'MyModule' which IMO means the declaration was being processed from both the original location and the new location. I believe this implies the original location was valid as well.
I've tried turning the logging on but the instructions in CONTRIBUTING.md are not clear to me, my apologies. I've put the NODE_DEBUG variable to system variables (I'm on Windows) with value tsify browserify and I've put var log = require('util').debuglog(require('./package').name); to my guplfile.js but I'm not sure what to do next.

How TypeScript resolves modules - and what it considers to be valid - does not matter. What might matter is how Browserify does it. And what Browserify considers to be valid.

The algorithm used by Browserify - and Node - is explained here.

I'm also a Windows developer. I would not recommend putting the environment variable into the system variables. Specify it on the command line and use Git Bash or a similar shell.

The following locations for the ambient declaration were tried and with no success

./node_modules/@types/mymodule/index.d.ts
./node_modules/@types/mymodule.d.ts

Again, when I tried to keep the file in both of these locations the Gulp task complained about a duplicate identifier. I believe this means the file was, in fact, found. Therefore I believe the error is not in the location.

Another reason to believe the locations are correct is that when I completely remove the file there is not 1 error but 2 errors in the Gulp task execution:
TypeScript error: src/consumer.ts(1,24): Error TS2307: Cannot find module 'mymodule'. Error: Cannot find module 'mymodule' from 'D:\Projects\Playground\TSTest\src'

And I'm sorry, I'm having no luck with setting up the logging. I've put NODE_DEBUG into my .bashrc and I'm running Gulp from within Git Bash. But I have no idea what to do next in order to actually see some more info about my error from within Browserify/Tsify.

The environment variable doesn't go into a configuration file; it's specified on the command line, immediately before the command you want to run - as in the doc to which I referred you.

The duplicate error you are.getting is a TS error. The initial error you mentioned in the issue is - IMO - most likely a Browserify error. Have a looks at what tsc generates when it 'works'. Is there a require for this ambient module? If there is, that is likely the problem.

Unfortunately, I no longer use tsify have never authored my own ambient modules and don't have the time to diagnose this problem for you.

Well, thanks for your effort anyway.

@mnovotny

@mnovotny I encountered the same situation as you, and found the answer. Maybe the same method can help you too.

I got the initial answer from here

For you, I first suppose the final calling of MyModule.Report could be rewritten to window.MyModule.Report. If it is not right, you may need to modify the config option.

In package.json at the root directory of the project, adding module browserify-shim(or just npm install browserify-shim) and config options for it. At last, it would be like:

{
    "devDependencies": {
        "browserify-shim": "*"
    },
    "browserify-shim": {
        "mymodule": "global:window"
    },
    "browserify": {
        "transform": [
            "browserify-shim"
        ]
    }
}

That's all :)

In consumer.js, the compiled code is like this:

var mymodule_1 = (typeof window !== "undefined" ? window['window'] : typeof global !== "undefined" ? global['window'] : null);

mymodule_1.MyModule.Report("MyModule was found by consumer");

The browserify-shim plugin treats mymodule as a external module and use another variable name to replace it, just like using external and output.global with rollup

Hope it will help you.

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Cannot find ambient module declaration in .d.ts #256

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cartant commented on Aug 6, 2019

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