fix: properly skip comment lines

Author: shellscape

index.js

@@ -133,6 +133,14 @@ class CsvParser extends Transform {
     let isQuoted = false
     let offset = start
 
+    const { skipComments } = this
+    if (skipComments) {
+      const char = typeof skipComments === 'string' ? skipComments : '#'
+      if (buf[start] === bufferFrom(char)[0]) {
+        return
+      }
+    }
+
     const mapValue = (value) => {
       if (this._first) {
         return value
@@ -144,14 +152,6 @@ class CsvParser extends Transform {
       return this.mapValues({ header, index, value })
     }
 
-    const { skipComments } = this
-    if (skipComments) {
-      const char = typeof skipComments === 'string' ? skipComments : '#'
-      if (buf[0] === bufferFrom(char)) {
-        return
-      }
-    }
-
     for (let i = start; i < end; i++) {
       const isStartingQuote = !isQuoted && buf[i] === this.quote
       const isEndingQuote = isQuoted && buf[i] === this.quote && i + 1 <= end && buf[i + 1] === comma

test/skipComments.test.js

@@ -6,7 +6,7 @@ test.cb('comment', (t) => {
   const verify = (err, lines) => {
     t.false(err, 'no err')
     t.snapshot(lines)
-    t.is(lines.length, 2, '2 rowa')
+    t.is(lines.length, 1, '1 row')
     t.end()
   }
 
@@ -17,7 +17,7 @@ test.cb('custom comment', (t) => {
   const verify = (err, lines) => {
     t.false(err, 'no err')
     t.snapshot(lines)
-    t.is(lines.length, 2, '2 rows')
+    t.is(lines.length, 1, '1 row')
     t.end()
   }
 

test/snapshots/comment.test.js.md

@@ -10,10 +10,9 @@ Generated by [AVA](https://ava.li).
 
     [
       Row {
-        '# comment': 'a',
-      },
-      Row {
-        '# comment': '1',
+        a: '1',
+        b: '2',
+        c: '3',
       },
     ]
 
@@ -23,9 +22,8 @@ Generated by [AVA](https://ava.li).
 
     [
       Row {
-        '~ comment': 'a',
-      },
-      Row {
-        '~ comment': '1',
+        a: '1',
+        b: '2',
+        c: '3',
       },
     ]