23 lines
642 B
Markdown
23 lines
642 B
Markdown
---
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tags:
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- backend
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- node-js
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---
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# Ports
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When working in development we are able to specify the specific port from which
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we want top serve our application. In production, we do not always have this
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control: the port will most likely be set by the provider of the server
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environment.
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While we may not know the specific port, whatever it is, it will be accessible
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via the `PORT` environment variable. So we can use this when writing our
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[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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```
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This way, if a port is set by the provider it will use it. If not, it will fall
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back to 3000.
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