1 files changed, 12 insertions, 3 deletions
diff --git a/std/node/os.ts b/std/node/os.ts
index ee64bfceb..c5e0f6c76 100644
--- a/std/node/os.ts
+++ b/std/node/os.ts
@@ -19,6 +19,7 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 import { notImplemented } from "./_utils.ts";
+import { EOL as fsEOL } from "../fs/eol.ts";
 
 const SEE_GITHUB_ISSUE = "See https://github.com/denoland/deno/issues/3802";
 
@@ -96,9 +97,17 @@ export function cpus(): CPUCoreInfo[] {
   notImplemented(SEE_GITHUB_ISSUE);
 }
 
-/** Not yet implemented */
+/**
+ * Returns a string identifying the endianness of the CPU for which the Deno
+ * binary was compiled. Possible values are 'BE' for big endian and 'LE' for
+ * little endian.
+ **/
 export function endianness(): "BE" | "LE" {
-  notImplemented(SEE_GITHUB_ISSUE);
+  // Source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView#Endianness
+  const buffer = new ArrayBuffer(2);
+  new DataView(buffer).setInt16(0, 256, true /* littleEndian */);
+  // Int16Array uses the platform's endianness.
+  return new Int16Array(buffer)[0] === 256 ? "LE" : "BE";
 }
 
 /** Not yet implemented */
@@ -201,7 +210,7 @@ export const constants = {
   }
 };
 
-export const EOL = Deno.build.os == "win" ? "\r\n" : "\n";
+export const EOL = Deno.build.os == "win" ? fsEOL.CRLF : fsEOL.LF;
 
 const validateInt32 = (
   value: number,