node flags must be passed to node, not ts-node

[cspotcode]

If you want to use various node flags with ts-node, you must pass them to node directly. For example, here we are loading ts-node and also passing node's -gc flag:

node -r ts-node/register -gc ./index.ts

Node also supports a NODE_OPTIONS environment variable, explained in node's official documentation. You can use that environment variable with ts-node.

NODE_OPTIONS="-gc" ts-node-script ./index.ts

If you're curious why we do this, you can read this issue, which explains why spawning a subprocess causes other problems. #471

Remember that the examples above are written in bash syntax. If you're using Windows PowerShell or cmd, they have buggy, confusing, and/or limiting behavior for parsing a command-line and setting environment variables. ts-node uses node's standard process.argv and process.env. We are not responsible for how they are parsed or passed into the node process. If a Windows shell is not giving us the correct process.argv or process.env values, then this is the fault of the Windows shell.

To debug the values being passed to ts-node, try this:

ts-node --transpile-only -p -e "console.dir(process.argv)"
ts-node --transpile-only -p -e "console.dir(process.execArgv)"
ts-node --transpile-only -p -e "console.dir(process.env)"

node -p "console.dir(process.argv)"
node -p "console.dir(process.execArgv)"
node -p "console.dir(process.env)"

Remember also that npm uses a cmd shim for all installed binaries. This means when you run ts-node, you are invoking a cmd.exe batch script, which invokes node, passing it the path to ts-node's entrypoint .js file. This behavior is controlled by npm, and there are certain limitations and quirks imposed by this cmd shim.

In the debugging examples above, the first 3 are using this cmd shim. The last 3 are not. If you see discrepancies, it is caused by the limitations and quirks of npm's cmd shim.

[cspotcode]

If the information above can be improved in any way, please ask questions here and we will update it accordingly.

[Glench]

Thanks for sharing! Setting the NODE_OPTIONS environment variable was really helpful to pass the -C flag to node.