getBodySize (body.ts)

Calculates body size from stream or content-length for HTTP client requests/responses.

import type {Options} from '../types/options.js';
import {usualFormBoundarySize} from '../core/constants.js';

const encoder = new TextEncoder();

// eslint-disable-next-line @typescript-eslint/no-restricted-types
export const getBodySize = (body?: BodyInit | null): number => {
	if (!body) {
		return 0;
	}

	if (body instanceof FormData) {
		// This is an approximation, as FormData size calculation is not straightforward
		let size = 0;

		for (const [key, value] of body) {
			size += usualFormBoundarySize;
			size += encoder.encode(`Content-Disposition: form-data; name="${key}"`).byteLength;
			size += typeof value === 'string'
				? encoder.encode(value).byteLength
				: value.size;
		}

		return size;
	}

	if (body instanceof Blob) {
		return body.size;
	}

	if (body instanceof ArrayBuf

... (truncated -- full source via MCP)