add help prompt

installer/mod.ts

@@ -135,11 +135,20 @@ async function fetchModule(url: string): Promise<string> {
  return decoder.decode(body);
 }
 
-async function main(): Promise<void> {
+function showHelp(): void {
+ console.log(`USAGE:
+deno https://deno.land/std/installer/mod.ts SCRIPT [FLAGS...] 
+
+ARGS:
+ SCRIPT URL of script to install
+ [FLAGS...] List of flags for script
+ `);
+}
+
+async function install(moduleUrl: string, flags: string[]): Promise<void> {
  let installerDir = getInstallerDir();
  createDirIfNotExists(installerDir);
 
- const moduleUrl: string = args[1];
  // TODO: handle local modules as well
  if (!moduleUrl.startsWith("http")) {
  throw new Error("Only remote modules are supported.");
@@ -169,7 +178,7 @@ async function main(): Promise<void> {
 
  const grantedPermissions: Permission[] = [];
 
- for (const flag of args.slice(2)) {
+ for (const flag of flags) {
  const permission = getPermissionFromFlag(flag);
  if (permission === Permission.Unknown) {
  continue;
@@ -192,7 +201,7 @@ async function main(): Promise<void> {
  await makeExecutable.status();
  makeExecutable.close();
 
- console.log(`✅  Successfully installed ${moduleName}.\n`);
+ console.log(`✅ Successfully installed ${moduleName}.\n`);
  // TODO: display this prompt only if `installerDir` not in PATH
  // TODO: add Windows version
  console.log("ℹ️ Add ~/.deno/bin to PATH");
@@ -201,15 +210,30 @@ async function main(): Promise<void> {
  );
 }
 
-// TODO: refactor
-try {
- main();
-} catch (e) {
- const err = e as Error;
- if (err.message) {
- console.log(err.message);
- } else {
- console.log(e);
+async function main(): Promise<void> {
+ if (args.length < 2) {
+ return showHelp();
+ }
+
+ const moduleUrl = args[1];
+ const flags = args.slice(2);
+
+ if (moduleUrl == "-h" || "--help") {
+ return showHelp();
+ }
+
+ // TODO: refactor
+ try {
+ await install(moduleUrl, flags);
+ } catch (e) {
+ const err = e as Error;
+ if (err.message) {
+ console.log(err.message);
+ } else {
+ console.log(e);
+ }
+ exit(1);
  }
- exit(1);
 }
+
+main();