I am trying to do 2 ajax function calls when a user clicks a button.
I have
$('.test').on('click', function(){
code.getCode();
code.getText();
})
code.prototype.getCode=function(){
var call=//call ajax
call.callback= function(data){
//parse return data
}
}
code.prototype.getText=function(){
var call=//call ajax
call.callback= function(data){
//parse return data
}
}
I can only do 1 ajax call and only 1 ajax call will return data.
I am not sure how to solve this. Any ideas? Thanks a lot!
I am not sure if I understood correctly, but I think you are looking for a single callback from both the ajax calls..
You should use $.when.done. See below,
$.when($.ajax("/page1.php"), $.ajax("/page2.php")).done(function(a1, a2){
/* a1 and a2 are arguments resolved for the
page1 and page2 ajax requests, respectively */
var jqXHR = a1[2]; /* arguments are [ "success", statusText, jqXHR ] */
if ( /Whip It/.test(jqXHR.responseText) ) {
alert("First page has 'Whip It' somewhere.");
}
});
Not sure if you looking for sequencing it or trying to have 1 callback.
You could also have the first ajax call, call the second on success:
$('.test').on('click', function(){
var datastr = "your data";
$.ajax({
type: "POST",
url: "url",
data: datastr,
success: function(successMsg) {
//ajax done
if (/* not yet complete */) {
setTimeout(secondAjaxCall(),500);
} else {
secondAjaxCall();
}
}
});
});
You could just save each return in the code object (since you are in a different context you have to work around "this"). Then you can use a third function that checks if the data objects are loaded... and start parsing once both are there.
$('.test').on('click', function(){
code.getCode();
code.getText();
})
code.prototype.getCode=function(){
var call=//call ajax
var that = this;
call.callback= function(data){
//parse return data
that.codeData = data;
parseData();
}
}
code.prototype.getText=function(){
var call=//call ajax
var that = this;
call.callback= function(data){
//parse return data
that.textData = data;
parseData();
}
}
function parseData() {
if(!code.textData || !code.codeData) return;
... work with both
}
Related
I need to execute 3 ajax requests. I know that they happen to be asynchronous by default (And making them synchronous messes up the VM, so I don't want to go that way.) The way I do it is by calling a function three times passing variables.
result = '';
parse(var1);
parse(var2);
parse(var3);
view();
function parse(variable) {
//ajax request here
$.ajax({
type: 'POST',
url: 'script.php',
data: {variable: variable},
success: function (data) {
//result stored in a global variable
result += data;
}
});
}
function view() {
//do something with result
}
But right now, the view() is triggered right away when the result isn't done cooking. How do I set them up to happen one after the other? I read about callbacks but they are very confusing since I don't have 3 distinct functions but just one taking different variables.
You could store your variables in an array and use a function to make your ajax call:
var variables = [var1, var2, var3];
function callParse() {
if(variables.length) {
var currentVar = variables.shift();
parse(currentVar);
}
else {
view();
}
}
function parse(variable){
//ajax request here
$.ajax({
type:"POST",
url:'script.php',
data:{variable:variable},
success:function(data)
{
result+=data;
callParse();
}
});
}
function view(){
//do something with result
}
Try chained promises - from: https://css-tricks.com/multiple-simultaneous-ajax-requests-one-callback-jquery/
$.when(
// Get the HTML
$.get("/feature/", function(html) {
globalStore.html = html;
}),
// Get the CSS
$.get("/assets/feature.css", function(css) {
globalStore.css = css;
}),
// Get the JS
$.getScript("/assets/feature.js")
).then(function() {
// All is ready now, so...
// Add CSS to page
$("<style />").html(globalStore.css).appendTo("head");
// Add HTML to page
$("body").append(globalStore.html);
});
You could try doing it this way:
parseAndView([var1, var2, var3]);
function parseAndView(vars, index) {
index = index || 0; //initialize index if not passed
//execute the AJAX call only if there are more variables to parse
if (index < vars.length)
//ajax request here
$.ajax({
type: "POST",
url: 'script.php',
data: {variable: vars[index]},
success: function (data) {
// result stored in a global variable
result += data;
// recursive call to parse another variable
parseAndView(vars, index++);
}
});
else
view();
}
function view() {
//do something with result
}
I am trying to create a database handler class in javascript. I would like to call the class by simply using:
var databaseHandler = new DatabaseHandler();
result = databaseHandler.getResult("SELECT * FROM login");
I have created the class and used a callback for the ajax function (so as to wait for the ajax result to be returned). But all I am still receiving "undefined" as my result. If I use console.log(a) inside of the onComplete function, I get an array of the intended results.
(function(window){
//Database class
function DatabaseHandler(){
//Query
this.query = function(query, whenDone){
request = $.ajax({
url: "../optiMizeDashboards/php/DatabaseQuery.php",
type: "POST",
data: {query : query},
dataType: "JSON"
});
request.done(function(output) {
whenDone(output);
});
request.fail(function(jqXHR, textStatus) {
console.log(textStatus);
});
};
//Get result
this.getResult = function(query){
this.query(query, this.onComplete);
};
//Ajax callback
this.onComplete = function(a){
return a;
};
}
//Make available to global scope
window.DatabaseHandler = DatabaseHandler;
}(window))
My question is: Is this something to do with the variable scope, or the way that ajax works? I have read all the answers explaining that ajax is ASYNC and I thought I had handled that by using a callback function "onComplete"
Any help on this topic would be greatly appreciated!
You will not be able to return result immediately from calling getResult because underlying jQuery POST request is Asynchronous, instead you need to be passing a callback function which eventually will receive a result from server.
something like that:
(function(window){
//Database class
function DatabaseHandler(){
//Query
this.query = function(query, whenDone){
request = $.ajax({
url: "../optiMizeDashboards/php/DatabaseQuery.php",
type: "POST",
data: {query : query},
dataType: "JSON"
});
request.done(function(output) {
whenDone(output);
});
request.fail(function(jqXHR, textStatus) {
console.log(textStatus);
});
};
//Get result
this.getResult = function(query, callback){
this.query(query, callback);
};
}
//Make available to global scope
window.DatabaseHandler = DatabaseHandler;
}(window))
// then use it like so
var databaseHandler = new DatabaseHandler();
result = databaseHandler.getResult("SELECT * FROM login", function(data) {
//do something with data
});
PS: exposing direct SQL access to the databse on the client is very dangerous though, and I would not recommend doing that
I have created a small JavaScript application with the following function that calls a function to retrieve JSON data:
var months = function getMonths(){
$.getJSON("app/data/Cars/12Months", function (some_data) {
if (some_data == null) {
return false;
}
var months_data = new Array();
var value_data = new Array();
$.each(some_data, function(index, value) {
months_data.push(index);
value_data.push(value);
});
return[months_data,value_data];
});
}
I have then created, in the same file, another function that does something when a specific page is loaded. In this function the variable 'months' is passed to the variable 'result'.
$(document).on('pageshow', '#chartCar', function(){
$(document).ready(function() {
var result = months;
var date = result[0];
var values = result[1];
//more code here...
});
}
the problem is that, based on the debugger, the getMonths() function works fine and produces the expected output, but the 'result' variable in the second function can't obtain the values passed to it by the variable 'months'. Do you know how to solve this issue?
The problem is that you $.getJSON() function is asynchronous, so your data gets loaded later then you read it. There're two workarounds:
1. Replace your $.getJSON with $.ajax and setting async: false;
2. Put your code in $.getJSON callback:
var months = function getMonths(){
$.getJSON("app/data/Cars/12Months", function (some_data) {
if (some_data == null) {
return false;
}
var months_data = new Array();
var value_data = new Array();
$.each(some_data, function(index, value) {
months_data.push(index);
value_data.push(value);
});
var date = months_data;
var values = value_data;
//more code here..
})
}
There must be a syntax error.
replace
});
}
With
});
});
$.getJSON() is a wrapper around $.ajax which is async by default. But you treat it like a sync call.
You can use $.ajaxSetup()
$.ajaxSetup( { "async": false } );
$.getJSON(...)
$.ajaxSetup( { "async": true } );
or use $.ajax with async: false
$.ajax({
type: 'GET',
url: 'app/data/Cars/12Months',
dataType: 'json',
async: false,
success: function(some_data) {
//your code goes here
}
});
or if possible change the behavior of your app so that you process your data in a callback function.
I have an issue with a method ive created for an object ive created. one of the methods requires a callback to another method. the problem is i cant add the data to the object that called the method. it keeps coming back as undefined. otherwise when i send the data to the console it is correct. how can i get the data back to the method?
var blogObject = new Object();
var following = [...];
//get posts from those blogs
blogObject.getPosts = function () {
var followersBlogArray = new Array();
for (var i = 0; i < this.following.length;i++){
var followersBlog = new Object();
// get construct blog url
var complete_blog_url = ...;
i call the getAvatar function here sending the current user on the following array with it.
followersBlog.avatar = blogObject.getAvatar(this.following[i]);
that part goes smoothly
followersBlogArray.push(followersBlog);
}
this.followersBlogArray = followersBlogArray;
}
here is the function that gets called with the current user in following array
this function calls an ajax function
blogObject.getAvatar = function (data) {
console.log("get avatar");
var url = "..."
this ajax function does its work and has a callback function of showAvatar
$(function() {
$.ajax({
type: "GET",
dataType: "jsonp",
cache: false,
url: url,
data: {
jsonp:"blogObject.showAvatar"
}
});
});
}
this function gets called no problem when getAvatar is called. i cant however get it to add the data to the followersBlog object.
blogObject.showAvatar = function (avatar) {
return avatar
}
everything in here works fine but i cant get the showAvatar function to add to my followersBlog object. ive tried
blogObject.showAvatar = function (avatar) {
this.followersBlog.avatar = avatar;
return avatar
}
that didnt work of course. it shows up as undefined. can anyone help?
so somethings like...
$(function() {
$.ajax({
type: "GET",
dataType: "jsonp",
cache: false,
url: url,
complete: function () {
this.avatar = data;
}
data: {
jsonp:"blogObject.showAvatar"
}
});
});
}
Welcome to the world of asynchronous programming.
You need to account for the fact that $.ajax() will not return a value immediately, and Javascript engines will not wait for it to complete before moving on to the next line of code.
To fix this, you'll need to refactor your code and provide a callback for your AJAX call, which will call the code that you want to execute upon receiving a response from $.ajax(). This callback should be passed in as the complete argument for $.ajax().
The correct option for setting the JSONP callback is jsonpCallback. The recommendation from the API for .ajax(...) is to set it as a function.
{
// ...
jsonpCallback: function (returnedData) {
blogObject.showAvatar(returnedData);
},
// ...
}
I want to create a separate function to get specific data from Facebook graph JSON.
For example, I have the load() and called getNextFeed() function.
The getNextFeed works correctly. Except that returning value of aString is not successful.
When I pop alert(thisUrl). It said undefined.
Note: I am new to Javascript and Jquery. Please give me more information where I did wrong. Thank you.
function load()
{
$(document).ready(function() {
var token = "AccessToken";
var url = "https://graph.facebook.com/me/home?access_token=" + token;
var thisUrl = getNextFeed(url);
alert(thisUrl); // return undefined
});
function getNextFeed(aUrl)
{
$.ajax({
type: "POST",
url: aUrl,
dataType: "jsonp",
success: function(msg) {
alert(msg.paging.next); // return correctly
var aString = msg.paging.next;
alert(aString); // return correctly
return aString;
}
});
}
The problem is that $.ajax() is an ansynchronous function, means, when called, it returns in the same instance, but an ajax call is done in a separate thread. So your return vaule of $.ajax() is always undefined.
You have to use the ajax callback function to do whatever you need to do: Basically you already did it correctly, just that return aString does not return to your original caller function. So what you can do is to call a function within the callback (success()), or implement the logic directly within the success() function.
Example:
function load()
{
$(document).ready(function() {
var token = "AccessToken";
var url = "https://graph.facebook.com/me/home?access_token=" + token;
getNextFeed(url);
alert('Please wait, loading...');
});
function getNextFeed(aUrl)
{
$.ajax({
type: "POST",
url: aUrl,
dataType: "jsonp",
success: function(msg) {
alert(msg.paging.next); // return correctly
var aString = msg.paging.next;
alert(aString); // return correctly
do_something_with(aString);
}
});
}