2 files changed, 12 insertions, 84 deletions

diff --git a/cli/js/web/encode_utf8.ts b/cli/js/web/encode_utf8.ts
deleted file mode 100644
index 04e2560b7..000000000
--- a/cli/js/web/encode_utf8.ts
+++ /dev/null
@@ -1,80 +0,0 @@
-// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-// The following code is based off:
-// https://github.com/samthor/fast-text-encoding
-//
-// Copyright 2017 Sam Thorogood. All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License"); you may not
-// use this file except in compliance with the License. You may obtain a copy of
-// the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-// License for the specific language governing permissions and limitations under
-// the License.
-//
-
-export function encodeUtf8(input: string): Uint8Array {
-  let pos = 0;
-  const len = input.length;
-
-  let at = 0; // output position
-  let tlen = Math.max(32, len + (len >> 1) + 7); // 1.5x size
-  let target = new Uint8Array((tlen >> 3) << 3); // ... but at 8 byte offset
-
-  while (pos < len) {
-    let value = input.charCodeAt(pos++);
-    if (value >= 0xd800 && value <= 0xdbff) {
-      // high surrogate
-      if (pos < len) {
-        const extra = input.charCodeAt(pos);
-        if ((extra & 0xfc00) === 0xdc00) {
-          ++pos;
-          value = ((value & 0x3ff) << 10) + (extra & 0x3ff) + 0x10000;
-        }
-      }
-      if (value >= 0xd800 && value <= 0xdbff) {
-        continue; // drop lone surrogate
-      }
-    }
-
-    // expand the buffer if we couldn't write 4 bytes
-    if (at + 4 > target.length) {
-      tlen += 8; // minimum extra
-      tlen *= 1.0 + (pos / input.length) * 2; // take 2x the remaining
-      tlen = (tlen >> 3) << 3; // 8 byte offset
-
-      const update = new Uint8Array(tlen);
-      update.set(target);
-      target = update;
-    }
-
-    if ((value & 0xffffff80) === 0) {
-      // 1-byte
-      target[at++] = value; // ASCII
-      continue;
-    } else if ((value & 0xfffff800) === 0) {
-      // 2-byte
-      target[at++] = ((value >> 6) & 0x1f) | 0xc0;
-    } else if ((value & 0xffff0000) === 0) {
-      // 3-byte
-      target[at++] = ((value >> 12) & 0x0f) | 0xe0;
-      target[at++] = ((value >> 6) & 0x3f) | 0x80;
-    } else if ((value & 0xffe00000) === 0) {
-      // 4-byte
-      target[at++] = ((value >> 18) & 0x07) | 0xf0;
-      target[at++] = ((value >> 12) & 0x3f) | 0x80;
-      target[at++] = ((value >> 6) & 0x3f) | 0x80;
-    } else {
-      // FIXME: do we care
-      continue;
-    }
-
-    target[at++] = (value & 0x3f) | 0x80;
-  }
-
-  return target.slice(0, at);
-}
diff --git a/cli/js/web/text_encoding.ts b/cli/js/web/text_encoding.ts
index 2da53d934..5f04972aa 100644
--- a/cli/js/web/text_encoding.ts
+++ b/cli/js/web/text_encoding.ts
@@ -26,7 +26,7 @@
 import * as base64 from "./base64.ts";
 import { decodeUtf8 } from "./decode_utf8.ts";
 import * as domTypes from "./dom_types.ts";
-import { encodeUtf8 } from "./encode_utf8.ts";
+import { core } from "../core.ts";
 
 const CONTINUE = null;
 const END_OF_STREAM = -1;
@@ -352,6 +352,15 @@ export class TextDecoder {
       bytes = new Uint8Array(0);
     }
 
+    // For simple utf-8 decoding "Deno.core.decode" can be used for performance
+    if (
+      this._encoding === "utf-8" &&
+      this.fatal === false &&
+      this.ignoreBOM === false
+    ) {
+      return core.decode(bytes);
+    }
+
     // For performance reasons we utilise a highly optimised decoder instead of
     // the general decoder.
     if (this._encoding === "utf-8") {
@@ -396,10 +405,9 @@ interface TextEncoderEncodeIntoResult {
 export class TextEncoder {
   readonly encoding = "utf-8";
   encode(input = ""): Uint8Array {
-    // For performance reasons we utilise a highly optimised decoder instead of
-    // the general decoder.
+    // Deno.core.encode() provides very efficient utf-8 encoding
     if (this.encoding === "utf-8") {
-      return encodeUtf8(input);
+      return core.encode(input);
     }
 
     const encoder = new UTF8Encoder();