added check for typescript template and unsupported node version (facebook#7839)

* added check for typescript template and unsupported node version * addressed code review feedback regarding syntax and spelling mistakes

Author: awaseem

packages/create-react-app/createReactApp.js

@@ -193,6 +193,26 @@ function createApp(
  useTypescript,
  template
 ) {
+ const unsupportedNodeVersion = !semver.satisfies(process.version, '>=8.10.0');
+ if (unsupportedNodeVersion && useTypescript) {
+ console.log(
+ chalk.red(
+ `You are using Node ${process.version} with the TypeScript template. Node 8.10 or higher is required to use TypeScript.\n`
+ )
+ );
+
+ process.exit(1);
+ } else if (unsupportedNodeVersion) {
+ console.log(
+ chalk.yellow(
+ `You are using Node ${process.version} so the project will be bootstrapped with an old unsupported version of tools.\n\n` +
+ `Please update to Node 8.10 or higher for a better, fully supported experience.\n`
+ )
+ );
+ // Fall back to latest supported react-scripts on Node 4
+ version = 'react-scripts@0.9.x';
+ }
+
  const root = path.resolve(name);
  const appName = path.basename(root);
 
@@ -222,17 +242,6 @@ function createApp(
  process.exit(1);
  }
 
- if (!semver.satisfies(process.version, '>=8.10.0')) {
- console.log(
- chalk.yellow(
- `You are using Node ${process.version} so the project will be bootstrapped with an old unsupported version of tools.\n\n` +
- `Please update to Node 8.10 or higher for a better, fully supported experience.\n`
- )
- );
- // Fall back to latest supported react-scripts on Node 4
- version = 'react-scripts@0.9.x';
- }
-
  if (!useYarn) {
  const npmInfo = checkNpmVersion();
  if (!npmInfo.hasMinNpm) {