/***
* 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;
}
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