@mparticle/web-sdk/src/uploaders.ts

mParticle core SDK for web applications

type HTTPMethod = 'get' | 'post';

export interface IFetchPayload {
    method: string;
    headers: {
        Accept: string;
        'Content-Type'?: string;
    };
    body?: string;
}

export abstract class AsyncUploader {
    url: string;
    public abstract upload(
        fetchPayload: IFetchPayload,
        url?: string
    ): Promise<Response>;

    constructor(url: string) {
        this.url = url;
    }
}

export class FetchUploader extends AsyncUploader {
    public async upload(
        fetchPayload: IFetchPayload,
        _url?: string
    ): Promise<Response> {
        const url = _url || this.url;
        return await fetch(url, fetchPayload);
    }
}

export class XHRUploader extends AsyncUploader {
    public async upload(fetchPayload: IFetchPayload): Promise<Response> {
        const response: Response = await this.makeRequest(
            this.url,
            fetchPayload.body,
            fetchPayload.method as HTTPMethod,
            fetchPayload.headers
        );
        return response;
    }

    // XHR Ready States
    // https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/readyState
    // 0   UNSENT  open() has not been called yet.
    // 1   OPENED  send() has been called.
    // 2   HEADERS_RECEIVED    send() has been called, and headers and status are available.
    // 3   LOADING Downloading; responseText holds partial data.
    // 4   DONE    The operation is complete.

    // https://go.mparticle.com/work/SQDSDKS-6736
    private async makeRequest(
        url: string,
        data: string,
        method: HTTPMethod = 'post',
        headers: Record<string, string> = {}
    ): Promise<Response> {
        const xhr: XMLHttpRequest = new XMLHttpRequest();
        return new Promise((resolve, reject) => {
            xhr.onreadystatechange = () => {
                if (xhr.readyState !== 4) return;

                // Process the response
                // We resolve all xhr responses whose ready state is 4 regardless of HTTP codes that may be errors (400+)
                // because these are valid HTTP responses.
                resolve((xhr as unknown) as Response);
            };

            // Reject a promise only when there is an xhr error
            xhr.onerror = () => {
                reject((xhr as unknown) as Response);
            };

            xhr.open(method, url);

            for (const key in headers) {
                if (headers.hasOwnProperty(key)) {
                    xhr.setRequestHeader(key, headers[key]);
                }
            }

            xhr.send(data);
        });
    }
}