How to insert a Build Number or Timestamp at build time in AngularCLI

1. Install plugin npm install replace-in-file --save-dev

2. Add to prod environment src/environments/environment.prod.ts new
   property

   export const environment = {
       production: true,
       version: '{BUILD_VERSION}'
   }
   

3. Add build file replace.build.js to root of your folder

   var replace = require('replace-in-file');
   var buildVersion = process.argv[2];
   const options = {
       files: 'src/environments/environment.prod.ts',
       from: /{BUILD_VERSION}/g,
       to: buildVersion,
       allowEmptyPaths: false,
   };
   
   try {
       let changedFiles = replace.sync(options);
       console.log('Build version set: ' + buildVersion);
   }
   catch (error) {
       console.error('Error occurred:', error);
   }
   

4. add scripts to package.json

   "updateBuild": "node ./replace.build.js"
   

5. Use environment.version in your app

6. Before build call npm run updateBuild -- 1.0.1

PS. You must always remember that {BUILD_VERSION} is never committed.

PS. I wrote a bit better solution in my blog

PS.3 as @julien-100000 mentioned you should not commit environment.prod.ts with updated version. Version update must happen only in build process. And should never be committed.