add hw2

node_modules/@pkgjs/parseargs/examples/no-repeated-options.js

@@ -0,0 +1,31 @@
+'use strict';
+
+// This is an example of using tokens to add a custom behaviour.
+//
+// Throw an error if an option is used more than once.
+
+// 1. const { parseArgs } = require('node:util'); // from node
+// 2. const { parseArgs } = require('@pkgjs/parseargs'); // from package
+const { parseArgs } = require('..'); // in repo
+
+const options = {
+  ding: { type: 'boolean', short: 'd' },
+  beep: { type: 'boolean', short: 'b' }
+};
+const { values, tokens } = parseArgs({ options, tokens: true });
+
+const seenBefore = new Set();
+tokens.forEach((token) => {
+  if (token.kind !== 'option') return;
+  if (seenBefore.has(token.name)) {
+    throw new Error(`option '${token.name}' used multiple times`);
+  }
+  seenBefore.add(token.name);
+});
+
+console.log(values);
+
+// Try the following:
+//    node no-repeated-options --ding --beep
+//    node no-repeated-options --beep -b
+//    node no-repeated-options -ddd