Add CSV and TSV parsing.

Author: mbostock

README.md

@@ -303,7 +303,7 @@ const url = await FileAttachment("file.txt").url();
 Returns a promise to the file’s contents as a JavaScript string.
 
 ```js
-const data = d3.csvParse(await FileAttachment("cars.csv").text());
+const hello = await FileAttachment("hello.txt").text();
 ```
 
 <a href="#attachment_json" name="attachment_json">#</a> *attachment*.<b>json</b>() [<>](https://github.com/observablehq/stdlib/blob/master/src/fileAttachment.js "Source")
@@ -314,6 +314,26 @@ Returns a promise to the file’s contents, parsed as JSON into JavaScript value
 const logs = await FileAttachment("weekend-logs.json").json();
 ```
 
+<a href="#attachment_csv" name="attachment_csv">#</a> *attachment*.<b>csv</b>({<i>array</i> = false, <i>typed</i> = false} = {}) [<>](https://github.com/observablehq/stdlib/blob/master/src/fileAttachment.js "Source")
+
+Returns a promise to the file’s contents, parsed as comma-separated values (CSV) into an array.
+
+```js
+const data = await FileAttachment("cars.csv").csv();
+```
+
+If <i>array</i> is true, an array of arrays is returned; otherwise, the first row is assumed to be the header row and an array of objects is returned, and the returned array has a <i>data</i>.columns property that is an array of column names. (See <a href="https://github.com/d3/d3-dsv/blob/master/README.md#dsv_parseRows">d3.csvParseRows</a>.) If <i>typed</i> is true, [automatic type inference](https://observablehq.com/@d3/d3-autotype) is applied; only use this feature if you know your data is compatible.
+
+<a href="#attachment_csv" name="attachment_tsv">#</a> *attachment*.<b>tsv</b>({<i>array</i> = false, <i>typed</i> = false} = {}) [<>](https://github.com/observablehq/stdlib/blob/master/src/fileAttachment.js "Source")
+
+Returns a promise to the file’s contents, parsed as tab-separated values (TSV) into an array.
+
+```js
+const data = await FileAttachment("cars.tsv").tsv();
+```
+
+If <i>array</i> is true, an array of arrays is returned; otherwise, the first row is assumed to be the header row and an array of objects is returned, and the returned array has a <i>data</i>.columns property that is an array of column names. (See <a href="https://github.com/d3/d3-dsv/blob/master/README.md#dsv_parseRows">d3.tsvParseRows</a>.) If <i>typed</i> is true, [automatic type inference](https://observablehq.com/@d3/d3-autotype) is applied; only use this feature if you know your data is compatible.
+
 <a href="#attachment_image" name="attachment_image">#</a> *attachment*.<b>image</b>() [<>](https://github.com/observablehq/stdlib/blob/master/src/fileAttachment.js "Source")
 
 Returns a promise to a file loaded as an [Image](https://developer.mozilla.org/en-US/docs/Web/API/HTMLImageElement/Image). The promise resolves when the image has finished loading, making this useful for reading the image pixels in Canvas, or for loading the image into a WebGL texture. Consider [*attachment*.url](#attachment_url) if you want to embed an image in HTML or Markdown.

src/fileAttachment.js

@@ -1,9 +1,18 @@
+import {require as requireDefault} from "d3-require";
+
 async function remote_fetch(file) {
   const response = await fetch(await file.url());
   if (!response.ok) throw new Error(`Unable to load file: ${file.name}`);
   return response;
 }
 
+async function dsv(file, delimiter, {array = false, typed = false} = {}) {
+  const [text, d3] = await Promise.all([file.text(), requireDefault("[email protected]/dist/d3-dsv.min.js")]);
+  return (delimiter === "\t"
+      ? (array ? d3.tsvParseRows : d3.tsvParse)
+      : (array ? d3.csvParseRows : d3.csvParse))(text, typed && d3.autoType);
+}
+
 class FileAttachment {
   constructor(url, name) {
     Object.defineProperties(this, {
@@ -29,6 +38,12 @@ class FileAttachment {
   async stream() {
     return (await remote_fetch(this)).body;
   }
+  async csv(options) {
+    return dsv(this, ",", options);
+  }
+  async tsv(options) {
+    return dsv(this, "\t", options);
+  }
   async image() {
     const url = await this.url();
     return new Promise((resolve, reject) => {