I'm doing my first mobile app with jquery mobile and phonegap/cordova. All goes great until I create the pages themselves, but as soon as I want to access some variables i access from the remote server, it fails at specific places. I already tried about 30 variations re-writing the same code again - literally spent 4 hours already on outputting a simple var -, but no success, and i simply pulling my remaining hair out now.
Here's my code snip
I have an html file, a js file and a php on serverside, outputting a json answer
php response i get:
{"item":{"ID":"1","fname":"Kris","lname":"Nagy","email":"myemail#email.com","password":"abc123","role":"1","practice":"0","address":"","city":"","zip":"","phone":""}}
login.js
var userName;
function getUser() {
$.getJSON( "http://myserver.com/getuser.php?email=myemail#email.com&pass=absc123", function( json ) {
console.log( "JSON Data: " + json.item.fname );
console.log( "JSON Data: " + json.item.email );
// testing if i have the correct data, console outputs the rigth values
userName = = json.item.fname;
window.userName = json.item.fname;
//trying to assign value to variable
console.log( "Variable data" + window.userName );
// testing if i have the correct data stored, console outputs the right value
});
}
getUser();
console.log( "test outside function" + window.userName );
//gives back undefined
index.html (here I'm just trying to access the variable, sure i have the full html, including the js, jquery and all necessities)
<script>
getUser(); //outputs the values to console
console.log( "test in html" + window.userName ); /*/gives back undefined
</script>
As i need some vars in my html to work with, how do i achieve to be able to output them in the html. This example tries to make some kind of login, but my question is more abotu the variables, as i want to understand them. In my understanding I have global variables with the window. call, but it seems everything but to be global, and I'll need to work with variables all along the app, so its vital i understand them. Though as you see it seems i miss a point, so any help is so appreciated.
I know how to work with php, but as the final product needs to run on cordova, I'm limited to html/js on the client side, and javascript is not my strength (yet).
You could return the promise interface exposed by ajax request from your function:
var userName;
function getUser() {
return $.getJSON(...);
}
getUser().done(function () {
console.log("test outside function" + window.userName);
});
You cannot access userName outside the JSON success callback, since you are assigning teh value only in success callback of an asynchronous method.
console.log( "test outside function" + window.userName ); // it wont work
If you still want to access immediately, make synchronous call by setting one of ajax settings async:false, but the overall goal of ajax is lost
Related
Edit/Clarification: I have a php page, call it displayPhotos.php, in which I set up an Ajax call to a different php page, call it getPhotos.php, which queries a database and returns photo information (caption, file name etc) to displayPhotos.php where they are displayed. I use php in displayPhotos to manipulate the data returned from getPhotos. The returned data from the Ajax call is a javascript 2-dimensional array. I need to turn the javascript array into a php array so I can do they display and other stuff. How do I do that?
Hope this helps.
My eyes hurt from reading all of the docs.
I want to use ajax to query a database, return the data then use php to continue with the web page.
All of the examples I've looked at start with creating the json in php. I need to start with the json object in javascript.
<script>
var photoarray = [];
var ajaxRequest = $.ajax
({
url : "fhs_get_photos.php",
type: "POST",
dataType: "json",
success: function(photo_array)
{
photoarray = photo_array;
//line below works. the file name is correct but disappears
//outside of this function
console.log("photoarray[0][file_name] is: " + photoarray[0]['file_name']);
},
error: function(request, status, error)
{
alert('An error occurred: ' );
}
});
In this instance I'm not passing anything to the php file that query's the db. The console log shows that the file name in photoarray is correct but once outside of this function it disappears even though it's declared as global, I think it is anyway. Why and what do I need to do to fix this.
The php file just does a SELECT * FROM..... and returns everything.
// in fhs_get_photos.php
// SELECT * FROM table......
echo $json = json_encode($result);
return $json;
So I now have the array back but it's in javascript. Once I figure out the scope problem, how can I convert this javascript array to a php array?
<h3>Welcome to the Historical Society's historical photo archive
</h3>
</header>
<figure id="photo_figure">
<script>
//line below gets me: SCRIPT5007: Unable to get property 'thumb' of
//undefined or null reference
console.log("photoarray thumb: ") + photoarray[0]['thumb'];
</script>
Am I explaining this properly?
First of all AJAX is async. This means it sends the request when you ask it to, but receives the response sometime later in the future. And it works after php has rendered and sent the page. So. When you get an update via AJAX, you have to use javascript to make that update matter. The most simple solution is to process the response right there in the success callback. That way you don't need to mess with the global scope (which is a bad practice).
Supposedly, your HTML is like this:
<header>
<h3>Welcome to the Historical Society's historical photo archive
</h3>
</header>
<div id="figures"></div>
You can do it by declaring a function that handles the processing:
function updateDom(photoArr) {
var $figures = $('#figures');
$.each(photoArr, function() {
console.log(this);
$figures.append('<img src="' + this.thumb +'">');
});
}
Code below is placed in the success callback
And execute that function in the success callback and pass it the array from json, that was parsed and became a valid js object.
var photoArray = JSON.parse(photo_array);
updateDom(photoArray);
here's the fiddle, but it's for the DOM part only
Im building a windows 8 app (html)
And have a api im fetching data from.
I keep getting this error however
0x800a138f - JavaScript runtime error: Unable to get property 'json' of undefined or null reference
in my scripts1.js file. then my program crashes -_-.
Here is the the code i use
$(function () {
startRefresh();
});
function startRefresh() {
setTimeout(startRefresh, 10000);
var url = 'http://pubapi.cryptsy.com/api.php?method=singlemarketdata&marketid=132';
$.getJSON('http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20json%20where%20url%3D%22' + encodeURIComponent(url) + '%22&format=json', function (data) {
jQuery('#ticker').html(data['query'].results.json.return.markets.DOGE.lasttradeprice);
jQuery('#ticker').append(' ' + data['query'].results.json.return.markets.DOGE.secondarycode);
jQuery('#ticker2').html(data['query'].results.json.return.markets.DOGE.lasttradetime);
jQuery('#ticker3').html(data['query'].results.json.return.markets.DOGE.volume);
});
}
This is located in scripts1.js Then i use ect.
It works everything comes and displays just get that error. Not sure what to do.
Seems like data['query'].results is undefined. Pasting the JSON you get will help.
Also, one small piece of advice: If you are going to access an in-depth attribute and, specially, a DOM node several times, you might want to recycle a reference to it rather than travelling again and again to fetch it for performance reasons. Something like this:
var ticker = jQuery('#ticker');
var DOGE = data['query'].results.json.return.markets.DOGE;
ticker.html(DOGE.lasttradeprice);
...
It looks like, occasionally, the API will send back some JSON that, when parsed, doesn't contain a results object. To mitigate this you should put a condition in to catch this eventuality.
if (data.query.results) {
jQuery('#ticker').html(data['query'].results.json.return.markets.DOGE.lasttradeprice);
// rest of DOM update code
}
Demo.
I want to take an external json file (locations.json) and load the contents into a variable. I would then like to use this variable using the information provided here: http://www.json.org/js.html
I've had a lot of trouble trying to load the external json to a variable. I've looked at this ( load json into variable ) page quite a bit, and none of that actually populates the variable. When displaying the variable's contents later, it appears to be empty.
$("#testContain").html("<p>" + json + "</p>");
Using methods listed in the last link, this dispays "undefined".
The json file that I am using looks like this:
[{"id":"1","locname":"Dunstable Downs","lat":"51.8646","lng":"-0.536957","address":"Chiltern Gateway Centre","address2":"","city":"","state":"England","postal":"","phone":"","web":"http:\/\/www.nationaltrust.org.uk\/main\/w-dunstabledownscountrysidecentrewhipsnadeestate","hours1":"","hours2":"","hours3":""},
{"id":"2","locname":"West Delta Park","lat":"45.5974","lng":"-122.688","address":"N Broadacre St and N Expo Rd, Portland","address2":"","city":"","state":"OR","postal":"","phone":"","web":"http:\/\/en.wikipedia.org\/wiki\/Delta_Park","hours1":"","hours2":"","hours3":""}]
Anyone have any suggestions?
The problem is that the request is asynchronous. You could make a synchronous call as suggested by the accepted answer to the question that you linked to, but that is generally not a good idea as it will freeze the browser completely while it is waiting for the response.
The variable is assigned just fine, but when you use it after requesting it, you have to make sure that it's after getting the response, not just after sending the request. Using the value in the callback for the getJSON method is the easiest way to make sure that you have the value:
var my_json;
$.getJSON(my_url, function(json) {
my_json = json;
// here you have the value
});
// here you don't have the value, as this happens before the response arrives
I'm very, very new to Javascript, and to web programming in general. I think that I'm misunderstanding something fundamental, but I've been unable to figure out what.
I have the following code:
function checkUserAuth(){
var userAuthHttpObject = new XMLHttpRequest();
var url = baseURL + "/userAuth";
userAuthHttpObject.open("POST",url,true);
userAuthHttpObject.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
userAuthHttpObject.onload=function(){
if (userAuthHttpObject.readyState == 4) {
var response = json.loads(userAuthHttpObject.responseText);
return response; //This is the part that doesn't work!
}
};
userAuthHttpObject.send(params);
}
I would love to call it from my page with something like:
var authResponse = checkUserAuth();
And then just do what I want with that data.
Returning a variable, however, just returns it to the userAuthObject, and not all the way back to the function that was originally called.
Is there a way to get the data out of the HttpObject, and into the page that called the function?
Working with AJAX requires wrapping your head around asynchronous behavior, which is different than other types of programming. Rather than returning values directly, you want to set up a callback function.
Create another JavaScript function which accepts the AJAX response as a parameter. This function, let's call it "takeAction(response)", should do whatever it needs to, perhaps print a failure message or set a value in a hidden field and submit a form, whatever.
then where you have "return response" put "takeAction(response)".
So now, takeAction will do whatever it was you would have done after you called "var authResponse = checkUserAuth();"
There are a couple of best practices you should start with before you continue to write the script you asked about
XMLHTTTPRequest() is not browser consistent. I would recommend you use a library such as mootools or the excellent jquery.ajax as a starting point. it easier to implement and works more consistently. http://api.jquery.com/jQuery.ajax/
content type is important. You will have have problems trying to parse json data if you used a form content type. use "application/json" if you want to use json.
true user authorization should be done on the server, never in the browser. I'm not sure how you are using this script, but I suggest you may want to reconsider.
Preliminaries out of the way, Here is one way I would get information from an ajax call into the page with jquery:
$.ajax({
//get an html chunk
url: 'ajax/test.html',
// do something with the html chunk
success: function(htmlData) {
//replace the content of <div id="auth">
$('#auth').html(htmlData);
//replace content of #auth with only the data in #message from
//the data we recieved in our ajax call
$('#auth').html( function() {
return $(htmlData).find('#message').text();
});
}
});
I am trying a straightforward remote json call with jquery. I am trying to use the reddit api. http://api.reddit.com. This returns a valid json object.
If I call a local file (which is what is returned from the website saved to my local disk) things work fine.
$(document).ready(function() {
$.getJSON("js/reddit.json", function (json) {
$.each(json.data.children, function () {
title = this.data.title;
url = this.data.url;
$("#redditbox").append("<div>" + title + "<div>");
});
});
});
If I then try to convert it to a remote call:
$(document).ready(function() {
$.getJSON("http://api.reddit.com", function (json) {
$.each(json.data.children, function () {
title = this.data.title;
url = this.data.url;
$("#redditbox").append("<div>" + title + "<div>");
});
});
});
it will work fine in Safari, but not Firefox. This is expect as Firefox doesnt do remote calls due to security or something. Fine.
In the jquery docs they say to do it like this (jsonp):
$(document).ready(function() {
$.getJSON("http://api.reddit.com?jsoncallback=?", function (json) {
$.each(json.data.children, function () {
title = this.data.title;
url = this.data.url;
$("#redditbox").append("<div>" + title + "<div>");
});
});
});
however it now stops working on both safari and firefox. The request is made but what is return from the server appears to be ignored.
Is this a problem with the code I am writing or with something the server is returning? How can I diagnose this problem?
EDIT Changed the address to the real one.
JSONP is something that needs to be supported on the server. I can't find the documentation, but it appears that, if Reddit supports JSONP, it's not with the jsoncallback query variable.
What JSONP does, is wrap the JSON text with a JavaScript Function call, this allows the JSON text to be processed by any function you've already defined in your code. This function does need to be available from the Global scope, however. It appears that the JQuery getJSON method generates a function name for you, and assigns it to the jsoncallback query string variable.
The URL you are pointing to (www.redit.com...) is not returning JSON! Not sure where the JSON syndication from reddit comes but you might want to start with the example from the docs:
$(document).ready(function() {
$.getJSON("http://api.flickr.com/services/feeds/photos_public.gne?tags=cat&tagmode=any&format=json&jsoncallback=?", function (data) {
$.each(data.items, function(i,item){
$("<img/>").attr("src", item.media.m).appendTo("#redditbox");
if ( i == 4 ) return false;
});
});
});
(apologies for formatting)
EDIT Now I re read your post, I see you intended to go to api.reddit.com unfortunately you haven't got the right parameter name for the json callback parameter. You might need to further consult the reddit documentation to see if they support JSONP and what the name of the callback param should be.
I'm not sure about reddit.com, but for sites that don't support the JSONP idiom you can still create a proxy technique (on the backend) that would return the reddit JSON, and then you would just make an ajax request to that that.
So if you called http://mydomain.com/proxy.php?url=http://api.reddit.com:
<?php
$url = $_GET["url"];
print_r(file_get_contents($url));
?>
http://api.reddit.com/ returns JSON, but doesn't appear to be JSONP-friendly. You can verify this, if you have GET, via
% GET http://api.reddit.com/?callback=foo
which dumps a stream of JSON without the JSONP wrapper.
http://code.reddit.com/browser/r2/r2/controllers/api.py (line 84) shows the code looking for 'callback' (not 'jsoncallback'). That may be a good starting point for digging through Reddit's code to see what the trick is.