public static void WriteEscapedJavaScriptString()

in src/Elastic.Apm/Libraries/Newtonsoft.Json/Utilities/JavaScriptUtils.cs [118:261]
119 lines of code
40 McCabe index (conditional complexity)

		public static void WriteEscapedJavaScriptString(TextWriter writer, string? s, char delimiter, bool appendDelimiters,
			bool[] charEscapeFlags, StringEscapeHandling stringEscapeHandling, IArrayPool<char>? bufferPool, ref char[]? writeBuffer
		)
		{
			// leading delimiter
			if (appendDelimiters) writer.Write(delimiter);

			if (!StringUtils.IsNullOrEmpty(s))
			{
				var lastWritePosition = FirstCharToEscape(s, charEscapeFlags, stringEscapeHandling);
				if (lastWritePosition == -1)
					writer.Write(s);
				else
				{
					if (lastWritePosition != 0)
					{
						if (writeBuffer == null || writeBuffer.Length < lastWritePosition)
							writeBuffer = BufferUtils.EnsureBufferSize(bufferPool, lastWritePosition, writeBuffer);

						// write unchanged chars at start of text.
						s.CopyTo(0, writeBuffer, 0, lastWritePosition);
						writer.Write(writeBuffer, 0, lastWritePosition);
					}

					int length;
					for (var i = lastWritePosition; i < s.Length; i++)
					{
						var c = s[i];

						if (c < charEscapeFlags.Length && !charEscapeFlags[c]) continue;

						string? escapedValue;

						switch (c)
						{
							case '\t':
								escapedValue = @"\t";
								break;
							case '\n':
								escapedValue = @"\n";
								break;
							case '\r':
								escapedValue = @"\r";
								break;
							case '\f':
								escapedValue = @"\f";
								break;
							case '\b':
								escapedValue = @"\b";
								break;
							case '\\':
								escapedValue = @"\\";
								break;
							case '\u0085': // Next Line
								escapedValue = @"\u0085";
								break;
							case '\u2028': // Line Separator
								escapedValue = @"\u2028";
								break;
							case '\u2029': // Paragraph Separator
								escapedValue = @"\u2029";
								break;
							default:
								if (c < charEscapeFlags.Length || stringEscapeHandling == StringEscapeHandling.EscapeNonAscii)
								{
									if (c == '\'' && stringEscapeHandling != StringEscapeHandling.EscapeHtml)
										escapedValue = @"\'";
									else if (c == '"' && stringEscapeHandling != StringEscapeHandling.EscapeHtml)
										escapedValue = @"\""";
									else
									{
										if (writeBuffer == null || writeBuffer.Length < UnicodeTextLength)
											writeBuffer = BufferUtils.EnsureBufferSize(bufferPool, UnicodeTextLength, writeBuffer);

										StringUtils.ToCharAsUnicode(c, writeBuffer!);

										// slightly hacky but it saves multiple conditions in if test
										escapedValue = EscapedUnicodeText;
									}
								}
								else
									escapedValue = null;
								break;
						}

						if (escapedValue == null) continue;

						var isEscapedUnicodeText = string.Equals(escapedValue, EscapedUnicodeText, StringComparison.Ordinal);

						if (i > lastWritePosition)
						{
							length = i - lastWritePosition + (isEscapedUnicodeText ? UnicodeTextLength : 0);
							var start = isEscapedUnicodeText ? UnicodeTextLength : 0;

							if (writeBuffer == null || writeBuffer.Length < length)
							{
								var newBuffer = BufferUtils.RentBuffer(bufferPool, length);

								// the unicode text is already in the buffer
								// copy it over when creating new buffer
								if (isEscapedUnicodeText)
								{
									MiscellaneousUtils.Assert(writeBuffer != null,
										"Write buffer should never be null because it is set when the escaped unicode text is encountered.");

									Array.Copy(writeBuffer, newBuffer, UnicodeTextLength);
								}

								BufferUtils.ReturnBuffer(bufferPool, writeBuffer);

								writeBuffer = newBuffer;
							}

							s.CopyTo(lastWritePosition, writeBuffer, start, length - start);

							// write unchanged chars before writing escaped text
							writer.Write(writeBuffer, start, length - start);
						}

						lastWritePosition = i + 1;
						if (!isEscapedUnicodeText)
							writer.Write(escapedValue);
						else
							writer.Write(writeBuffer, 0, UnicodeTextLength);
					}

					MiscellaneousUtils.Assert(lastWritePosition != 0);
					length = s.Length - lastWritePosition;
					if (length > 0)
					{
						if (writeBuffer == null || writeBuffer.Length < length)
							writeBuffer = BufferUtils.EnsureBufferSize(bufferPool, length, writeBuffer);

						s.CopyTo(lastWritePosition, writeBuffer, 0, length);

						// write remaining text
						writer.Write(writeBuffer, 0, length);
					}
				}
			}

			// trailing delimiter
			if (appendDelimiters) writer.Write(delimiter);
		}