Develop Reference

Trying to convert existing synchronous XmlHttpRequest object to be asynchronous to keep up with current fads

Soo, I keep getting slammed with cautions from Chrome about how synchronous XmlHttpRequest calls are being deprecated, and I've decided to have a go at trying to convert my use-case over in order to keep up with this fad...
In this case, I have an ~9 year old JS object that has been used as the central (and exemplary) means of transporting data between the server and our web-based applications using synchronous XHR calls. I've created a chopped-down version to post here (by gutting out a lot of sanity, safety and syntax checking):
function GlobalData()
{
this.protocol = "https://";
this.adminPHP = "DataMgmt.php";
this.ajax = false;
this.sessionId = "123456789AB";
this.validSession = true;
this.baseLocation = "http://www.example.com/";
this.loadResult = null;
this.AjaxPrep = function()
{
this.ajax = false;
if (window.XMLHttpRequest) {
try { this.ajax = new XMLHttpRequest(); } catch(e) { this.ajax = false; } }
}
this.FetchData = function (strUrl)
{
if ((typeof strURL=='string') && (strURL.length > 0))
{
if (this.ajax === false)
{
this.AjaxPrep();
if (this.ajax === false) { alert('Unable to initialise AJAX!'); return ""; }
}
strURL = strURL.replace("http://",this.protocol); // We'll only ask for data from secure (encrypted-channel) locations...
if (strURL.indexOf(this.protocol) < 0) strURL = this.protocol + this.adminPHP + strURL;
strURL += ((strURL.indexOf('?')>= 0) ? '&' : '?') + 'dynamicdata=' + Math.floor(Math.random() * this.sessionId);
if (this.validSession) strURL += "&sessionId=" + this.sessionId;
this.ajax.open("GET", strURL, false);
this.ajax.send();
if (this.ajax.status==200) strResult = this.ajax.responseText;
else alert("There was an error attempting to communicate with the server!\r\n\r\n(" + this.ajax.status + ") " + strURL);
if (strResult == "result = \"No valid Session information was provided.\";")
{
alert('Your session is no longer valid!');
window.location.href = this.baseLocation;
}
}
else console.log('Invalid data was passed to the Global.FetchData() function. [Ajax.obj.js line 62]');
return strResult;
}
this.LoadData = function(strURL)
{
var s = this.FetchData(strURL);
if ((s.length>0) && (s.indexOf('unction adminPHP()')>0))
{
try
{
s += "\r\nGlobal.loadResult = new adminPHP();";
eval(s);
if ((typeof Global.loadResult=='object') && (typeof Global.loadResult.get=='function')) return Global.loadResult;
} catch(e) { Global.Log("[AjaxObj.js] Error on Line 112: " + e.message); }
}
if ( (typeof s=='string') && (s.trim().length<4) )
s = new (function() { this.rowCount = function() { return -1; }; this.success = false; });
return s;
}
}
var Global = new GlobalData();
This "Global" object is referenced literally hundreds of times across 10's of thousands of lines code as so:
// Sample data request...
var myData = Global.LoadData("?fn=fetchCustomerData&sortByFields=lastName,firstName&sortOrder=asc");
if ((myData.success && (myData.rowCount()>0))
{
// Do Stuff...
// (typically build and populate a form, input control
// or table with the data)
}
The server side API is designed to handle all of the myriad kinds of requests encountered, and, in each case, to perform whatever magic is necessary to return the data sought by the calling function. A sample of the plain-text response to a query follows (the API turns the result(s) from any SQL query into this format automatically; adjusting the fields and data to reflect the retrieved data on the fly; the sample data below has been anonymized;):
/* Sample return result (plain text) from server:
function adminPHP()
{
var base = new DataInterchangeBase();
this.success = true;
this.colName = function(idNo) { return base.colName(idNo); }
this.addRow = function(arrRow) { base.addRow(arrRow); }
this.get = function(cellId,rowId) { return base.getByAbsPos(cellId,rowId); }
this.getById = function(cellId,rowId) { return base.getByIdVal(cellId,rowId); }
this.colExists = function(colName) { return ((typeof colName=='string') && (colName.length>0)) ? base.findCellId(colName) : -1; }
base.addCols( [ 'id','email','firstName','lastName','namePrefix','nameSuffix','phoneNbr','companyName' ] );
this.id = function(rowId) { return base.getByAbsPos(0,rowId); }
this.email = function(rowId) { return base.getByAbsPos(1,rowId); }
this.firstName = function(rowId) { return base.getByAbsPos(2,rowId); }
this.lastName = function(rowId) { return base.getByAbsPos(3,rowId); }
this.longName = function(rowId) { return base.getByAbsPos(5,rowId); }
this.namePrefix = function(rowId) { return base.getByAbsPos(6,rowId); }
this.nameSuffix = function(rowId) { return base.getByAbsPos(7,rowId); }
this.companyName = function(rowId) { return base.getByAbsPos(13,rowId); }
base.addRow( [ "2","biff#nexuscons.com","biff","broccoli","Mr.","PhD","5557891234","Nexus Consulting",null ] );
base.addRow( [ "15","happy#daysrhere.uk","joseph","chromebottom","Mr.","","5554323456","Retirement Planning Co.",null ] );
base.addRow( [ "51","michael#sunrisetravel.com","mike","dolittle","Mr.","",""5552461357","SunRise Travel",null ] );
base.addRow( [ "54","info#lumoxchemical.au","patricia","foxtrot","Mrs,","","5559876543","Lumox Chem Supplies",null ] );
this.query = function() { return " SELECT `u`.* FROM `users` AS `u` WHERE (`deleted`=0) ORDER BY `u`.`lastName` ASC, `u`.`firstName` LIMIT 4"; }
this.url = function() { return "https://www.example.com/DataMgmt.php?fn=fetchCustomerData&sortByFields=lastName,firstName&sortOrder=asc&dynamicdata=13647037920&sessionId=123456789AB\"; }
this.rowCount = function() { return base.rows.length; }
this.colCount = function() { return base.cols.length; }
this.getBase = function() { return base; }
}
*/
In virtually every instance where this code is called, the calling function cannot perform its work until it receives all of the data from the request in the object form that it expects.
So, I've read a bunch of stuff about performing the asynchronous calls, and the necessity to invoke a call-back function that's notified when the data is ready, but I'm a loss as to figuring out a way to return the resultant data back to the original (calling) function that's waiting for it without having to visit every one of those hundreds of instances and make major changes in every one (i.e. change the calling code to expect a call-back function as the result instead of the expected data and act accordingly; times 100's of instances...)
Sooo, any guidance, help or suggestions on how to proceed would be greatly appreciated!

API Key with colon, parsing it gives TypeError: forEach isn't a function

I'm trying to use New York Times API in order to get the Top Stories in JSON but I keep on getting a:
Uncaught TypeError: top.forEach is not a function
I feel like there's something wrong with the API key since it has : colons in the url. I even tried to encode it with %3A but it still doesn't work.
This is the basic url:
http://api.nytimes.com/svc/topstories/v2/home.json?api-key={API-KEY}
My function that grabs the data from the url:
```
function topStories(topStoriesURL) {
$.getJSON(topStoriesURL, function(top) {
top.forEach(function(data) {
link = data.results.url;
cardTitle = data.results.title;
if(data.results.byline == "") { postedBy = data.results.source; }
else { postedBy = data.results.byline; }
imgSource = data.results.media[0].media-metadata[10].url;
createCardElements();
});
});
}
I console.log(url) and when I click it inside Chrome console, it ignored the part of the key that comes after the colon. I've been debugging, but I can't seem to figure out the error.

Here is a version of the code that works.
function topStories(topStoriesURL) {
$.getJSON(topStoriesURL, function(data) {
if (data.error) {
alert('error!'); // TODO: Add better error handling here
} else {
data.results.forEach(function(result) {
var link = result.url,
cardTitle = result.title,
postedBy = result.byline == "" ? result.source : result.byline,
hasMultimedia = (result.multimedia || []).length > 0,
imgSource = hasMultimedia ? result.multimedia[result.multimedia.length - 1].url : null;
createCardElement(link, cardTitle, postedBy, imgSource);
});
}
});
}
function createCardElement(link, title, postedBy, imgSource) {
// create a single card element here
console.log('Creating a card with arguments of ', arguments);
}
topStories('http://api.nytimes.com/svc/topstories/v2/home.json?api-key=sample-key');

You are most likely going to need to do a for ... in loop on the top object since it is an object. You can not do a forEach upon on object the syntax would probably look like this:
function topStories(topStoriesURL) {
$.getJSON(topStoriesURL, function(top) {
for (var datum in top) {
link = datum.results.url;
cardTitle = datum.results.title;
if(datum.results.byline == "") { postedBy = datum.results.source; }
else { postedBy = datum.results.byline; }
imgSource = datum.results.media[0].media-metadata[10].url;
createCardElements();
});
});
}
Heres the documentation on for...in loops

Durandal: how to cache calls?

In my durandal app I need to know if the user is logged in different places. So currently i'm doing a call to get the user state in every views that needs it.
Is possible to do something like this:
//login.js
define(function(require) {
var http = require('durandal/http')
var isLogged;
function getLogin() {
if (isLogged != undefined) return isLogged
return http.get('/api/login').then(function(data) {
isLogged = data.logged
return isLogged
})
}
return {
getLogin: getLogin
}
//view.js
define(function(require) {
var login = require('login')
function vm() {
var self = this;
self.isLogged;
self.activate = function() {
self.isLogged = login.getLogin()
}
}
return vm
})
The above doesn't work because in the view activate method I need to return a promise. How can I achieve that?

You can use guardRouter function!
This will be triggered in all navigation.
// Shell main or other file that runs before any view!
// Define the router guard function!
require('plugin/router', 'Q', function(router, q){
var cache = {};
router.guardRoute = function(instance, instruction) {
var key = instruction.fragment.toLowerCase();
return cache[key] !== undefined ?
cache[key]:
q($.get(url,data)).then(_setCache, _fail);
function _fail(/*jqhxr*/) {
/* do something */
}
function _setCache(result) {
cache[key] = result;
return cache[key];
}
}
});
If you return true, the navigation will proceed! in case of string returned, durandal will navigate into it!
The cache works as you define (check for javascript memoization)
About durandal Auth chech this gitHub for inspiration.

Meteor call template method from another method

I want to call a method within a method for clientside but I don't know how to handle it, i've tried by calling like myFunction()and this.myFunction() but it is not working... This is my code
Template.decision.rendered = function () {
if ($(".active").length == 0) {
var random = Math.floor(Math.random() * 1000);
var $items = $(".item");
$items.eq(random % $items.length).addClass("active");
}
$.each($(".item"), function (index, value) {
if (Session.get($(this).attr('id'))) {
this.showResults(value.option);
}
});
};
Template.decision.showResults = function($option) {
$('#result').html('Option ' + $option + ' is voted');
};
As you can see I want to call showResults for each item inside rendered callback...

Found it using Template.decision.showResults(); silly me.

I think that a better way depending on what you are trying to do would be either to use a Session variable or a Meteor Method:
Session Variable.
Template.decision.created = function() {
Session.setDefault('showResults', false);
}
Template.decision.rendered = function() {
// [...]
$.each($(".item"), function (index, value) {
if (Session.get($(this).attr('id'))) {
Session.set('showResults', true);
}
});
}
Template.decision.showResults = function() {
return Session.get('showResults');
}
// in your template
<template name="decision">
{{#if showResults}}
<p>Here is the results.</p>
{{/if}}
</template>
Meteor Method.
// On the client.
Template.decision.rendered = function() {
// [...]
$.each($(".item"), function (index, value) {
if (Session.get($(this).attr('id'))) {
Meteor.call('showResults', function(error, result) {
if (!error and result === true) {
$('.class').hide() // It is here that you modify the DOM element according to the server response and your needs.
}
});
}
});
}
// Server-side method
// But, if you want it to react like a stub, put it inside your lib folder.
Meteor.methods({
showResults: function() {
// do your thing
result = true; // let's say everything works as expected on server-side, we return true
return result;
}
});

Prevent require.js to log itself to console

When I run this code in Chrome DevTool,
require(['common'], function (common) { common.getProfilPic(123); })
It always print the whole chunk of requirejs code,
function localRequire(deps, callback, errback) {
var id, map, requireMod;
if (options.enableBuildCallback && callback && isFunction(callback)) {
callback.__requireJsBuild = true;
}
if (typeof deps === 'string') {
if (isFunction(callback)) {
//Invalid call
return onError(makeError('requireargs', 'Invalid require call'), errback);
}
//If require|exports|module are requested, get the
//value for them from the special handlers. Caveat:
//this only works while module is being defined.
if (relMap && hasProp(handlers, deps)) {
return handlers[deps](registry[relMap.id]);
}
//Synchronous access to one module. If require.get is
//available (as in the Node adapter), prefer that.
if (req.get) {
return req.get(context, deps, relMap, localRequire);
}
//Normalize module name, if it contains . or ..
map = makeModuleMap(deps, relMap, false, true);
id = map.id;
if (!hasProp(defined, id)) {
return onError(makeError('notloaded', 'Module name "' +
id +
'" has not been loaded yet for context: ' +
contextName +
(relMap ? '' : '. Use require([])')));
}
return defined[id];
}
//Grab defines waiting in the global queue.
intakeDefines();
//Mark all the dependencies as needing to be loaded.
context.nextTick(function () {
//Some defines could have been added since the
//require call, collect them.
intakeDefines();
requireMod = getModule(makeModuleMap(null, relMap));
//Store if map config should be applied to this require
//call for dependencies.
requireMod.skipMap = options.skipMap;
requireMod.init(deps, callback, errback, {
enabled: true
});
checkLoaded();
});
return localRequire;
} require.js:1361
require(['common'], function (common) { console.log(common.getProfilPic(123)); })
function localRequire(deps, callback, errback) {
var id, map, requireMod;
if (options.enableBuildCallback && callback && isFunction(callback)) {
callback.__requireJsBuild = true;
}
if (typeof deps === 'string') {
if (isFunction(callback)) {
//Invalid call
return onError(makeError('requireargs', 'Invalid require call'), errback);
}
//If require|exports|module are requested, get the
//value for them from the special handlers. Caveat:
//this only works while module is being defined.
if (relMap && hasProp(handlers, deps)) {
return handlers[deps](registry[relMap.id]);
}
//Synchronous access to one module. If require.get is
//available (as in the Node adapter), prefer that.
if (req.get) {
return req.get(context, deps, relMap, localRequire);
}
//Normalize module name, if it contains . or ..
map = makeModuleMap(deps, relMap, false, true);
id = map.id;
if (!hasProp(defined, id)) {
return onError(makeError('notloaded', 'Module name "' +
id +
'" has not been loaded yet for context: ' +
contextName +
(relMap ? '' : '. Use require([])')));
}
return defined[id];
}
//Grab defines waiting in the global queue.
intakeDefines();
//Mark all the dependencies as needing to be loaded.
context.nextTick(function () {
//Some defines could have been added since the
//require call, collect them.
intakeDefines();
requireMod = getModule(makeModuleMap(null, relMap));
//Store if map config should be applied to this require
//call for dependencies.
requireMod.skipMap = options.skipMap;
requireMod.init(deps, callback, errback, {
enabled: true
});
checkLoaded();
});
return localRequire;
}
and and me from seeing the log result, and idea how to stop requirejs to print itself?

Run this instead:
(function(){ require(['common'], function (common) { common.getProfilPic(123); }) })()

What happens is that the console is printing out the value of the expression. The value of a function call is what the call returns. You can easily work around it with something like:
require(['common'], function (common) { common.getProfilPic(123); }); 1
Adding ; 1 will make the expression evaluate to 1. So you'll get 1 on the console but at least it won't push diagnostic messages off the screen.