Add Check If File Exists Before Reading It as a JavaScript TIL

javascript/check-if-file-exists-before-reading-it.md

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+# Check If File Exists Before Reading It
+
+Let's say we are working on a script that tries to read in existing data from a
+JSON data file. It is possible that data file hasn't been created and populated
+yet. In order to account for that scenario, we need to check if the file
+exists. If we try to read from a non-existant file, an error will be thrown.
+
+To prevent the script from error'ing out, we can use
+[`fs.existsSync`](https://nodejs.org/api/fs.html#fsexistssyncpath) to check if
+the given file path is an existing file. If we learn that the file does exist,
+we can proceed with reading it. If not, we can skip the file read and react
+accordingly.
+
+```javascript
+import fs from 'fs'
+
+const nonExistantFile = 'non-existant.json'
+
+// set default in case file does not exists
+let json = {}
+
+if(fs.existsSync(nonExistantFile)) {
+  const fileData = fs.readFileSync(nonExistantFile)
+  json = JSON.parse(fileData.toString())
+}
+
+console.log('JSON: ', json)
+```
+
+[source](https://flaviocopes.com/how-to-check-if-file-exists-node/)