fix(util-body-length-browser): handle trail surrogate character

Author: trivikr

packages/util-body-length-browser/src/calculateBodyLength.spec.ts

@@ -4,12 +4,12 @@ const arrayBuffer = new ArrayBuffer(1);
 const typedArray = new Uint8Array(1);
 
 describe(calculateBodyLength.name, () => {
-  it("should handle string inputs", () => {
-    expect(calculateBodyLength("foo")).toEqual(3);
-  });
-
-  it("should handle string inputs with multi-byte characters", () => {
-    expect(calculateBodyLength("2。")).toEqual(4);
+  it.each([
+    { desc: "basic", input: "foo", output: 3 },
+    { desc: "emoji", input: "foo 🥺", output: 8 },
+    { desc: "multi-byte characters", input: "2。", output: 4 },
+  ])("should handle string input: %s", ({ input, output }) => {
+    expect(calculateBodyLength(input)).toEqual(output);
   });
 
   it("should handle inputs with byteLengths", () => {

packages/util-body-length-browser/src/calculateBodyLength.ts

@@ -6,6 +6,7 @@ export const calculateBodyLength = (body: any): number | undefined => {
       const code = body.charCodeAt(i);
       if (code > 0x7f && code <= 0x7ff) len++;
       else if (code > 0x7ff && code <= 0xffff) len += 2;
+      if (code >= 0xdc00 && code <= 0xdfff) i--; //trail surrogate
     }
 
     return len;