From d9a45bbdba49446fa21bedb932653c9df2908006 Mon Sep 17 00:00:00 2001
From: Ardis Lu <ardisglu@gmail.com>
Date: Sat, 18 Oct 2025 21:17:43 -0700
Subject: [PATCH] Accept `string` as a shorthand for `{ name: string }`

It is common to set headers using all the default values, so it is useful to have a shorthand for this situation.
---
 src/normalization.js       | 41 +++++++++++++++++++++++++-------------
 test/normalization.test.js | 27 +++++++++++++++++++++++++
 2 files changed, 54 insertions(+), 14 deletions(-)

diff --git a/src/normalization.js b/src/normalization.js
index bc3cd09..32a57f9 100644
--- a/src/normalization.js
+++ b/src/normalization.js
@@ -115,8 +115,8 @@ export class CSVNormalizer extends TransformStream {
   #typeCastOnly;
 
   /**
-   * @param {Array<CSVNormalizerHeader>} headers An array of metadata objects to configure the data casting and
-   * cleanup transformations.
+   * @param {Array<CSVNormalizerHeader|string>} headers An array of `CSVNormalizerHeader` or `string` to configure the
+   * data casting and cleanup transformations. Passing a plain `string` is the same as passing `{ name: string }`.
    * @param {CSVNormalizerOptions} options Object containing flags to configure the stream logic. 
    */
   constructor(headers, options = {}) {
@@ -128,19 +128,32 @@ export class CSVNormalizer extends TransformStream {
     this.#passthroughEmptyRows = options.passthroughEmptyRows ?? false;
     this.#typeCastOnly = options.typeCastOnly ?? false;
 
-    for (const { name, type, displayName = name, defaultValue = '' } of headers) {
-      let normalizedType = type?.toLowerCase() ?? 'string';
-      if (!['string', 'number', 'bigint', 'date'].includes(normalizedType)) {
-        console.warn(`Type "${normalizedType}" is not supported, defaulting to string.`);
-        normalizedType = 'string';
+    for (const header of headers) {
+      if (typeof header === 'string') {
+        const name = this.#useLiteralNames ? header : toCamelCase(header);
+        this.#columns.push({
+          name,
+          type: 'string',
+          displayName: name,
+          defaultValue: '',
+          index: null
+        });
+      }
+      else {
+        const { name, type, displayName = name, defaultValue = '' } = header;
+        let normalizedType = type?.toLowerCase() ?? 'string';
+        if (!['string', 'number', 'bigint', 'date'].includes(normalizedType)) {
+          console.warn(`Type "${normalizedType}" is not supported, defaulting to string.`);
+          normalizedType = 'string';
+        }
+        this.#columns.push({
+          name: this.#useLiteralNames ? name : toCamelCase(name),
+          type: normalizedType,
+          displayName,
+          defaultValue,
+          index: null
+        });
       }
-      this.#columns.push({
-        name: this.#useLiteralNames ? name : toCamelCase(name),
-        type: normalizedType,
-        displayName,
-        defaultValue,
-        index: null
-      });
     }
   }
 
diff --git a/test/normalization.test.js b/test/normalization.test.js
index d71e0ae..d96e04b 100644
--- a/test/normalization.test.js
+++ b/test/normalization.test.js
@@ -252,6 +252,33 @@ suite('CSVNormalizer.toFieldMap', { concurrency: true }, () => {
 });
 
 suite('CSVNormalizer', { concurrency: true }, () => {
+  test('accepts string shorthand to set headers', { concurrency: true }, async () => {
+    await createCSVMockStream([
+      ['columnA', 'columnB'],
+      ['a', 'b']
+    ])
+      .pipeThrough(new CSVNormalizer(['columnA', 'columnB']))
+      .pipeThrough(new CSVDenormalizer())
+      .pipeTo(csvStreamEqualWritable([
+        ['columnA', 'columnB'],
+        ['a', 'b']
+      ]));
+  });
+  test('accepts mixed string and CSVNormalizerHeader to set headers', { concurrency: true }, async () => {
+    await createCSVMockStream([
+      ['columnA', 'columnB'],
+      ['a', 'b']
+    ])
+      .pipeThrough(new CSVNormalizer([
+        'columnA',
+        { name: 'columnB' }
+      ]))
+      .pipeThrough(new CSVDenormalizer())
+      .pipeTo(csvStreamEqualWritable([
+        ['columnA', 'columnB'],
+        ['a', 'b']
+      ]));
+  });
   test('can remove extra columns in CSV', { concurrency: true }, async () => {
     await createCSVMockStream([
       ['extra1', 'columnA', 'extra2', 'extra3', 'columnB'],
-- 
2.47.3