@frsource/frs-replace - replace content directly in your files/streams with ease (CLI included)! 📝

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The fastest (see benchmarks) CLI & Node wrapper around javascript replace which allows in-file replacing (with possibility to save changed file as a copy), globbing, piping and many more!

Getting Started (CLI) · Examples and recipes (CLI)
Getting Started (Node) · Examples and recipes (Node)

📜 Installation

npm install @frsource/frs-replace

or execute it right away:

npx @frsource/frs-replace

⌨️ CLI

frs-replace <regex><replacement> [flags]

Basic usage:

frs-replace something anything -i foo.js -o foo_replaced.js
# all of the occurences of "something" in `foo.js` will be replaced with "anything" and saved to `foo_replaced.js`

More examples below.

Arguments

Argument	Type	Description
<regex>	string	First parameter to RegExp constructor
<replacement>	string	String or path to replacement function file (see ‑‑replace‑fn switch for details)

Flags

Note: Every boolean option can be negated with use of --no- prefix, e.g. --stdout or --no-stdout turn stdout output on or off, respectively.

Note: Object types can be set using dot notation. So, e.g. if you want to pass utf8 value under i-read-optsencoding field you should write --i-read-opts.encoding utf8.

Option	Type	Default	Description
‑i, ‑‑input	string or string[]	-	Path to files or fast-glob pattern pointing to files to be read & replaced from. If multiple files specified results will be joined using outputJoinString option's value)
‑‑i-read-opts	string or object	utf8	Options which are passed directly to the readFileSync method when reading input file
‑‑i-glob-opts	object	undefined	Options which are passed directly to the fast-glob package when resolving glob patterns
‑‑stdin	boolean	true	Wait for stdin input (should be set to false when used in non-interactive terminals)
‑o, ‑‑output	string	-	Output file name/path (replaces the file if it already exists and creates any intermediate directories if they don't already exist)
‑‑o-write-opts	string or object	utf8	Passed as options argument of write's .sync
‑‑o-join-str	string	\n	Used when joining multiple files, passed directly to javascript join
‑c, ‑‑content	string	-	Content to be replaced (takes precedence over stream & file input)
‑s, ‑‑strategy	"join" or "flatten" or "preserve-structure"	"join"	Output file generation strategy. "join" - joins all input files and outputs them as a single file using path passed as: "output". "preserve-structure" - saves all files to the "output" directory keeping relative directory structure."flatten" - same as "preserve-structure" but flattens the directory structure
‑f, ‑‑flags	string, combination of gim flags	g	RegExp flags
‑‑stdout	boolean	true if piped input present, false otherwise	Force sending output on stdout
‑r, ‑‑replace‑fn	boolean	false	Treat replacement argument as path to file containing replacement function
‑h, ‑‑help	boolean	-	Show help
‑v, ‑‑version	boolean	-	Show version number

🔎 Examples and recipes - CLI

1. Replace all a occurrences with b from the foo.js file and return the result (using CLI)

frs-replace a b -i foo.js --stdout

2. Replace all a occurrences with b from foo.js and save the result to the foo_replaced.js (using CLI)

frs-replace a b -i foo.js -o foo_replaced.js

3. Replace all a occurrences with b from an array of files and save the result to the foo_replaced.js using default \n as a result-joining string (using CLI)

frs-replace a b -i foo.js -i foo2.js -o foo_replaced.js

4. Replace all a occurrences with b from all .js files in the foo directory and save the result to the foo_replaced.js using \n/////\n as a result-joining string (using CLI)

frs-replace a b -i foo/*.js -o foo_replaced.js --o-join-str "\n/////\n"

5. Replace all a occurrences with b in a content string abcd and save the result to the foo_replaced.js (using CLI)

frs-replace a b --content abcd -o foo_replaced.js

6. Replace all a occurrences with b from a piped stream and save it to the output file (using CLI)

<read-file>| frs-replace a b ><output-file-path>

7. Replace all a occurrences with b from a piped stream and pass it through the stdout stream to the <next-command> (using CLI)

<read-file>| frs-replace a b |<next-command>

📚 Node API

@frsource/frs-replace package is shipped in 2 flavors: synchronous and asynchronous:

import{sync,async}from'@frsource/frs-replace';sync({/* options */});awaitasync({/* options */});

Where /* options */ is an object containing:

Note: one of parameters: input or content is required

Option	Type	Default	Description
input	string or string[]	undefined	Path to files or fast-glob pattern pointing to files to be read & replaced from. If multiple files specified results will be joined using outputJoinString option's value)
inputReadOptions	string or object	utf8	Options which are passed directly to the readFileSync method when reading input file
inputGlobOptions	object	undefined	Options which are passed directly to the fast-glob package when resolving glob patterns
content	string	undefined	Content to be replaced (takes precedence over file input)
strategy	"join" or "flatten" or "preserve-structure"	"join"	Output file generation strategy. "join" - joins all input files and outputs them as a single file using path passed as: "output". "preserve-structure" - saves all files to the "output" directory keeping relative directory structure."flatten" - same as "preserve-structure" but flattens the directory structure
needle	string or RegExp Object	-	Used as a first argument of javascript replace
replacement	string	-	Passed as a second argument to javascript replace
output	string	undefined	Path of an output file
outputWriteOptions	string or object	"utf8"	Passed as options argument of write's .sync
outputJoinString	string	\n	String used when joining multiple files, passed directly to javascript join

🔎 Examples and recipes - Node

Note: While all of examples are using synchronous API method in all cases your can use async as well.

1. Replace all a occurrences with b from the foo.js file and return the result

import{sync}from'@frsource/frs-replace';constresult=sync({input: 'foo.js',regex: newRegExp('a','g'),replacement: 'b',output: 'foo_replaced.js',});

2. Replace all a occurrences with b from foo.js and save the result to the foo_replaced.js

import{sync}from'@frsource/frs-replace';constresult=sync({input: 'foo.js',regex: newRegExp('a','g'),replacement: 'b',output: 'foo_replaced.js',});

3. Replace all a occurrences with b from an array of files and save the result to the foo_replaced.js using default \n as a result-joining string

import{sync}from'@frsource/frs-replace';constresult=sync({input: ['foo.js','foo2.js'],regex: newRegExp('a','g'),replacement: 'b',output: 'foo_replaced.js',});

4. Replace all a occurrences with b from all .js files in the foo directory and save the result to the foo_replaced.js using \n/////\n as a result-joining string

import{sync}from'@frsource/frs-replace';constresult=sync({input: 'foo/*.js',regex: newRegExp('a','g'),replacement: 'b',outputJoinString: '\n/////\n',output: 'foo_replaced.js',});

5. Replace all a occurrences with b in a content string abcd and save the result to the foo_replaced.js

import{sync}from'@frsource/frs-replace';constresult=sync({content: 'abcd',regex: newRegExp('a','g'),replacement: 'b',output: 'foo_replaced.js',});

📈 Benchmarks

Tested on Node v24.20.0.

input as glob pattern [40 files]

Rank	Library	Average latency [ms]	Difference percentage (comparing to best average latency)
1	@frsource/frs-replace (sync)	0.30 ± 1.08%	+0.00%
2	replace-in-file (sync)	0.37 ± 2.10%	+23.88%
3	@frsource/frs-replace (async)	1.15 ± 1.97%	+286.47%
4	replace-in-file (async)	1.84 ± 1.68%	+514.53%

input & replacement as strings

Rank	Library	Average latency [ms]	Difference percentage (comparing to best average latency)
1	@frsource/frs-replace (sync)	0.00 ± 0.60%	+0.00%
2	replaceString	0.00 ± 0.58%	+23.33%
3	@frsource/frs-replace (async)	0.00 ± 0.56%	+32.00%