typescriptkit/src/HttpClient/HttpRequestExecutor.ts

Basic functionality for TypeScript projects

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import { ObjectExtensions } from '../Extensions/ObjectExtensions';
import { StringExtensions } from '../Extensions/StringExtensions';
import { IHttpRequestExecutor } from './IHttpRequestExecutor';

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/**
 * Implementation of the xmlHttpclient converting eventhandlers to callbacks (For internal use)
 */
export class HttpRequestExecutor implements IHttpRequestExecutor {

    /**
     * execte the Http GET call
     * @param url The url to point the request to
     * @param httpheaders (optional) The httpHeaders array to append to the request
     * @param success (optional) The callback after a succesfull request
     * @param error (optional) The callback after a failed request
     */
    public executeHttpGet = (url: string, httpHeaders?: Array<any>,
        success?: (responseText: string) => void,
        error?: (responseText: string, statusCode: number) => void): void => {
        if (StringExtensions.isNullOrWhitespace(url))
            throw new URIError('Please provide a valid URL to call to!');
        // Todo: validate url

        const httpRequest = new XMLHttpRequest();
        httpRequest.onreadystatechange = () => {
            if (httpRequest.readyState !== 4) return;
            if (httpRequest.status === 200) {
                success(httpRequest.responseText);
            } else {
                error(httpRequest.responseText, httpRequest.status);
            }
        };
        httpRequest.open(`GET`, url as any, true); // true for asynchronous
        if (!ObjectExtensions.isNullOrUndefined(httpHeaders) && httpHeaders.length > 0)
            this.applyRequestHeaders(httpRequest, httpHeaders);
        httpRequest.send(null);
    }

    private applyRequestHeaders(xmlHttp: XMLHttpRequest, httpHeaders: Array<any>): void {
        if (ObjectExtensions.isNullOrUndefined(httpHeaders)) return;

        for (let headerKey in httpHeaders) {
            if (!httpHeaders.hasOwnProperty(headerKey)) continue;
            const headerValue = httpHeaders[headerKey];
            xmlHttp.setRequestHeader(headerKey, headerValue);
        }
    }
}

export default HttpRequestExecutor;