javascript - What's the best way to overwrite a file using fs in node.js - Stack Overflow

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I'm trying to overwrite an existing file. I'm first checking if the file exists using:

fs.existsSync(path)

If file does not exit I'm creating and writing using:

fs.writeFileSync(path,string) 

The problem is when the file already exists and I want to over write all its contents. Is there a single line solution, so far I searched and found solutions that use fs.truncate & fs.write, but is there a one hit solution?

I'm trying to overwrite an existing file. I'm first checking if the file exists using:

fs.existsSync(path)

If file does not exit I'm creating and writing using:

fs.writeFileSync(path,string) 

The problem is when the file already exists and I want to over write all its contents. Is there a single line solution, so far I searched and found solutions that use fs.truncate & fs.write, but is there a one hit solution?

• javascript
• node.js

Share Improve this question Follow edited May 10, 2017 at 12:50 mihai 38.5k1111 gold badges6262 silver badges8989 bronze badges asked May 10, 2017 at 12:25 Tomas KatzTomas Katz 1,81433 gold badges1414 silver badges2929 bronze badges 2

• 10 Doesn't writeFileSync overwrite the file by default? – Quentin Commented May 10, 2017 at 12:27
• try this fs.writeFileSync(path, string, { flag: fs.constants.O_TRUNC | fs.constants.O_WRONLY }) – xuxu Commented Aug 9, 2022 at 7:43

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3 Answers 3

Sorted by: Reset to default 181

fs.writeFileSync and fs.writeFile overwrite the file by default, there is no need for extra checks if this is what you want to do. This is mentioned in the docs:

fs.writeFile

Asynchronously writes data to a file, replacing the file if it already exists.

Found the solution. fs.writeFileSync gets a third arguments for options that can be an object. So if you get the "File already exist" you should do.

fs.writeFileSync(path,content,{encoding:'utf8',flag:'w'})

When you say "best way", i think at performance and scalability and i'd say use the asynchronous method

fs.writeFileSync(path,string) as the name suggest is synchronous (blocking api) the thread is held for the whole lifecycle of the request, that means your nodejs thread will be blocked until the operation finishes and this behavior in a production environment with simultaneous connections from multiple clients could kill your app.

Do not think at the single line of code, less code doesn't mean better performance.

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