22 lines
965 B
Markdown
22 lines
965 B
Markdown
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---
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tags:
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- Programming_Languages
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- backend
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- node-js
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- node-modules
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---
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Like Bash, Node utilises [environment variables](../Shell%20Scripting/Environmental%20and%20shell%20variables.md) and the syntax is the same since Node must run in a Bash environment or emulator (like GitBash on Windows).
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When working in development we are able to specify the specific port from which we want top serve our application. In production, we do not always have this control: the port will most likely be set by the provider of the server environment.
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While we may not know the specific port, whichever it is, it will be accessible via the `PORT` environment variable. So we can use this when writing our [event listeners](Events%20module.md#event-emitters):
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````js
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const port = process.env.PORT || 3000;
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app.listen(port, () => console.log(`Listening on ${port}`));
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````
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This way, if a port is set by the provider it will use it. If not, it will fall back to 3000.
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