File: serverlink.js

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File: serverlink.js
Role: Auxiliary script
Content type: text/plain
Description: JS to promisify XMLHttp
Class: Web JSON Editor
Create data values in JSON format interactively
Author: By
Last change:
Date: 4 years ago
Size: 4,454 bytes
 

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/*** * Utility functions for interacting with a server * * Usage * docLoad(parmsObject).then(function(response){ * <doStuffAfterDocIsFullyLoaded using parmsObject>; * }); * getData(<servername>,<JsObjectTodespatch>).then(function(JsObjectAsResponse) { * <codeToDoSomethingWithTheresponse>; * }); * getrawData(<servername>,<dataTodespatch>).then(function(response) { * <codeToDoSomethingWithTheresponse>; * }); ***/ /*** * docload() - wait until document loaded before invoking '.then' * * @param mixed parms values to be passed to the .then process ***/ function docLoad(parms) { if(parms == undefined) parms = {}; let p = new Promise( function (resolve, reject) { window.addEventListener('load', function( ) { resolve(parms);}); window.addEventListener('error', function(e) { reject (e);}); }); return p; } /*** * getData() - promise to retrieve data from a URL * * Designed specifically to work with JSONServer.class.php. Expects a * specification of what is required as a Javascript object and returns * the server response as a Javascript object to the function specified * in the .then method. * * @param text url The location of the server (typically server.php) * @param json request A request which must conform to the expectations of * JSONServer.class.php * @resolve json A response object as served by JSONServer.class.php * @reject json A response object as served by * JSONServer.class.php or by getData itself * (e.g. if a transmission failure) ***/ function getData(url, request) { let key, requesttype, p, k requesttype = 's' if(request instanceof Array) { requesttype = 'a'; } else { for(key in request) { if (request[key] instanceof Object) { requesttype = 'o'; } break; } } p = new Promise( function (resolve, reject){ //retrieve data from server based on a spec using json format let xhttp = new XMLHttpRequest(); xhttp.onreadystatechange = function() { if (this.readyState == 4) { if (this.status == 200) { let response = JSON.parse(xhttp.responseText); if (requesttype == 's') { if (response.severity == 0) { resolve(response) } else { reject(response); } } else { let severity = 0; if(requesttype == 'a') { for (k=0; k<response.length; k++) { if (response[k].severity > severity) severity = response[k].severity; } } else { let keys = getkeys(response) for (key in keys) { if (response[k].severity > severity) severity = response[k].severity; } } response.severity = severity; if (severity > 0) reject(response); else resolve(response); } } else { let response = {}; response.resultData = {}; response.errorMessage = 'XHTTP:'+ this.status + ":" + xhttp.responseText, response.errorNum = 'CLIENT_1'; response.severity = 2; reject(response); } } }; xhttp.open("POST", url, true); xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); xhttp.send('data='+JSON.stringify(request)); }); return p; } /*** * getRawData() - promise to retrieve data from a URL * * Send an XMLHTTP request and wait for a response. Uses POST. * Returns the server response to the .then function * in the .then method. * * @param text url The location of the server/page * @param text request in the form parm1=value1&parm2=value2... * @resolve text The response from the server * @reject json A response object as served by * getRawData (e.g. if a transmission failure) ***/ function getRawData(url, data) //send the pre processed data to url and // releases the responseText when it is resolved { let p = new Promise( function (resolve, reject){ //retrieve data from server let xhttp = new XMLHttpRequest(); xhttp.onreadystatechange = function() { if (this.readyState == 4) { if (this.status == 200) { resolve(xhttp.responseText); } else { reject('XHTTP:'+ this.status); } } }; xhttp.open("POST", url, true); xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); xhttp.send('data='+data); }); return p; }