tree-shaking-server-side-code-7.ts

import * as ts from 'typescript';
import * as webpack from 'webpack';
import { AngularCompilerPlugin, PLATFORM } from '@ngtools/webpack';

const replaceIsPlatformCallsTransformerFactory: ts.TransformerFactory<ts.SourceFile> = (
  context: ts.TransformationContext,
) => (sourceFile: ts.SourceFile) => {
  const visitCallExpression: ts.Visitor = (node: ts.Node) => {
    if (ts.isCallExpression(node) && ts.isIdentifier(node.expression)) {
      // If it's a call expression like `isPlatformServer(platformId)`.
      if (node.expression.escapedText === 'isPlatformServer') {
        return ts.factory.createFalse();
      } else if (node.expression.escapedText === 'isPlatformBrowser') {
        return ts.factory.createTrue();
      }
    }

    return ts.visitEachChild(node, visitCallExpression, context);
  };

  return ts.visitEachChild(sourceFile, visitCallExpression, context);
};

export default (config: webpack.Configuration) => {
  const angularCompilerPlugin = config.plugins!.find(
    (plugin): plugin is AngularCompilerPlugin => plugin instanceof AngularCompilerPlugin,
  );

  const platform: PLATFORM = angularCompilerPlugin!['_platform'];
  if (platform === PLATFORM.Browser) {
    angularCompilerPlugin!['_transformers'].unshift(replaceIsPlatformCallsTransformerFactory);
  }

  return config;
};