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1.12.0 • Public • Published


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Devreplay is a static analysis tool based on your own programming rule. This introduced DevReplay rules information and CLI environment. Please check the following link for other platform information.

How to use

  1. Install on local
npm install -g devreplay
# or
yarn global add devreplay
  1. Put your own programming rule(.devreplay.json) on the project like bellow
  "before": [
  "after": [
    "$2, $3 = $3, $2"
  "isRegex": true
  1. Run the devreplay

or get fixed code

devreplay --fix

The target source code file will be

- tmp = a
- a = b
- b = a
+ a, b = b, a
  • Step up: Make the rule message and severity. Also after can be more abstract
  "before": [
  "after": [
    "$2, $3 = $3, $2"
  "isRegex": true,
  "author": "Yuki Ueda",
  "message": "Value exchanging can be one line",
  "severity": "Information"
  • severity means how this rule is important

    • E: Error
    • W: Warning
    • I: Information
    • H: Hint
  • Run devreplay again

$ devreplay
  15:1  warning  Value exchanging can be one line  0

Make rules

A JSON object represents a rule. The rule file .devreplay.json consists of a single rule or an array of rules.

Each rule comprises a pair of the before and after properties.

  • before property is the only DevReplay required property to find code fragments and show warnings for them.
  • after property is necessary for an automatic fix.

If the property is not specified, DevReplay shows a warning message. A value of the properties is either a single string or a string array. Using the array format, DevReplay finds and replaces the consecutive lines of code.

How to use Regular Expression

isRegex option regards the pattern specified in the before property as a regular expression. DevReplay uses the standard regular expression specified in ECMAScript 5. For example, the before property in the following example uses two ([a-z]+) representing any one or more characters.

In the after property, $1 and $2corresponds to the value enclosed in parentheses in the before property. Automatically generated coding rules enabled this option by default.

  "before": [
  "after": [
      "$1 $2"
  "isRegex": true

That will fix

- print("hello-world")
+ print("hello world")

More rule options

Option Type Detail
isRegex Boolean Use Regular Expression: Use JavaScript's regular expressions as specified in ECMAScript 5 to find the code. Auto generated coding rules have enabled this option.
wholeWord Boolean Match Whole Word: Search for a completely matched word (e.g. editor will not match with editors).
matchCase Boolean Match Case: Match lower or larger cases to searching code (e.g. editor will not match with Editor).
preserveCase Boolean Preserve Case: Preserving lower or larger cases for replacing code.
message String Message: Warning message on the VS Code panel and CLI output. Default message is before should be after.
severity String Severity: Rule severity. Changing severity means extending or reducing the rules' functions.
unnecessary String Unused or unnecessary code: The editor and CLI change the default message to before is unused'. Also, this property changes the behavior of the editor's representation from drawing a wavy line to graying the snippet text.
deprecated String Deprecated or obsolete code: The editor and CLI change the default message to before is deprecated'. Also, this property changes the editor's representation from wavy to strikethrough.

Supported Languages and Frameworks

You can enable built-in rules by writing a language or framework name directly in a rule file. For example, the following rule file enables TypeScript and Python rules. The built-in rules are defined in src/rules/[language-or-framework-name].ts files.

Languages Frameworks
C Android
CPP Angular
Cobol chainer2pytouch
Dart Rails
Java React
JavaScript TensorFlow
Python Vue

API Usage

You can use devreplay as a TypeScript API.

import {DevReplayRule, BaseRule2DevReplayRule, fixWithRules} from 'devreplay';

const rules: DevReplayRule[] = [{
    before: [
    after: [
        '$1 $2'
    isRegex: true
  before: [
    'for \\(let (?<i>.+) = 0;\\k<i> < (?<arr>.+).length;\\k<i>\\+\\+\\) (.*)\\(\\k<arr>\\[\\k<i>\\]\\)'
  after: [
    'for (let $1 = 0;$1 < $2.length;i++) {',
    '    $3($2[$1])',
  isRegex: true,
  message: 'One line for should use paren'
}].map(rule => BaseRule2DevReplayRule(rule, 0));

const fixed = fixWithRules('print("hello-world")', rules)
'print("hello world")'

const fixed2 = fixWithRules('for (let i = 0;i < arr.length;i++) foo(arr[i])', rules)
for (let i = 0;i < arr.length;i++) {

GitHub Actions

Please copy the following .github/workflows/devreplay.yml file to your repository.

name: Devreplay
on: [push, pull_request]
    runs-on: ubuntu-latest
      - uses: actions/checkout@v2
      - uses: actions/setup-node@v2
          node-version: "14.x"
      - run: npm install -g devreplay
      - name: Run devreplay
        run: devreplay ./ .devreplay.json

Contribution Link


  • Support rule ignoring comments
  • Support .devreplayignore file
  • Make rule generating GUI


MIT © 2019 Yuki Ueda (



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