piecemeal/piecemeal/index.js

Effortless incrementally deliver your data

'use strict';

const CONTENT_TYPE =  'content-type';
const message = (payload, headers) => {
    const returns = [''];
    for (let key in headers)
        returns.push(`${key}: ${headers[key]}`);
    returns.push('', String(payload), '');
    return returns.join('\r\n');
};
/*#__INLINE__*/
const is_raw = (data) => 'headers' in data && 'data' in data;
const generate = async (iterator, boundary, write, abort) => {
    await write(`--${boundary}`);
    for await (let data of iterator) {
        if (abort && abort.aborted)
            break;
        let payload = data, headers;
        let dtype = typeof data;
        if (data === null)
            payload = '';
        else if (dtype === 'object') {
            if (is_raw(data)) {
                headers = data.headers;
                payload = data.data;
            }
            else {
                headers = { [CONTENT_TYPE]: 'application/json;charset=utf-8' };
                payload = JSON.stringify(data);
            }
        }
        else if (dtype !== 'string') {
            payload = String(data);
        }
        headers = headers || { [CONTENT_TYPE]: 'text/plain' };
        await write(message(payload, headers) + `--${boundary}`);
    }
    write(`--\r\n`);
};

exports.generate = generate;
exports.message = message;