getJSON is not a function when the second time I called it - javascript

This is the first time I use jquery. The situation I'm facing here is that I need to parse some JSON file whose url is given by another JSON file.
Thus, I use the code
var GlobalID = {};
function parseID() {
var data;
$.getJSON('https://taitk.org/api/algorithms', function(algorithms) {
GlobalID = algorithms;
console.log("ID got!");
parseKeyword();
});
}
function parseKeyword () {
for(var i = 0; i < GlobalID.length; i++) {
$.getJSON('https://taitk.org/api/algorithms/' + GlobalID[i].id, function(subdata) {
console.log(subdata.data)
});
}
}
, where parseID() is a function to get the ID of each url, parseKeyword() is a function print out each url's data (written in the callback function, thus avoid the asynchronous function call).
However, the error I got is keyword.js:31 Uncaught TypeError: $.getJSON is not a function while the message "ID got!" is successfully printed. Also, the code work fine when I delete the parseKeyword()function, which is confusing for me because the first getJson() call seems to work while the second doesn't.
I'd like to figure out what kind of situation I'm facing to cause such error, thank you.
And, below is how I include those function in the html file:
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script></script>
<script src="js/keyword.js"></script>
<script type="text/javascript">
parseID()
</script>

The real cause is that I included the slim version of jquery in the <body> part along with the version mentioned in the question description. After removing it, it seems good.

Related

Jquery and javascript namepsace

In trying to namespace my js/jquery code, I have come up against the following problem.
Basically, I used to write all my JS code in each html/php file, and I want to abstract that away to a single js file with namespaces.
So, in my html file I have:
<script type="text/javascript">
$(document).ready(productActions.init());
</script>
And in my js file I have:
var productActions = {
init: function() {
alert('initialsed');
$('#field_id').change(function() {
alert('ok!');
});
}
The productActions init function is definitely running, because I get the first alert (initialised). However, it seems that none of the jquery binding functions do anything at all. Stepping through the init function shows that the above change function is being registered, but actually changing the value in the field does absolutely nothing.
Am I missing something obvious here?
$(document).ready(productActions.init());
This code calls init() immediately and passes its return value to ready(...). (just like any other function call)
Instead, you can write
$(document).ready(productActions.init);
To pass the function itself. Howeverm this will call it with the wrong this; if you need this, write
$(document).ready(function() { productActions.init() });

large text as parameter in javascript function

I would like to process large amount of text inside javascript, I tried to feed the text as a parameter to my js function
function processText(myText){
//do some task
}
It seems that javascript cannot pass the parameter correctly.
Is there any work around for this problem?
in the main code call processText function like:
$yourText=urlencode($originalText);
processText($yourText);
above is php code sample
function processText(myText) {
var lsRegExp = /\+/g
var properText=unescape(String(myText).replace(lsRegExp, " "));
// do something with properText
}

Javascript Uncaught TypeError : Object has no method

in my javascript application I am getting the following error upon page load.
Uncaught TypeError : Object #<Object> has no method 'showHideCleanupButton'
this appears (inside Chrome's debugger) to be blowing up inside the method 'getAllItemsForDisplay'where it calls 'this.showHideCleanupButton'
here is a link to it on jsFiddle:
http://jsfiddle.net/cpeele00/4fVys/
Any help would be greatly appreciated :-)
Thanks,
Chris
It appears that this is the relevant piece of code:
getAllItemsForDisplay: function() {
$.getJSON('services/act_getAllItems/', function(data) {
$('#items-list').empty();
$('#items-listTmpl').tmpl(data).appendTo('#items-list');
this.showHideCleanupButton();
BeefyUtils.noSelect();
});
},
What are you expecting this to be set to inside the getJSON callback? Have you set a breakpoint on the relevant statement and looked at what the value of this is?
If I understand the jQuery doc correct, by default this inside a getJSON call will be a reference to the ajax options that were originally passed in. I think it's possible to change what this will be with ajaxSetup, but I don't see that you've done that.
If you want to refer to the this at the beginning of getAllItemsForDisplay, then you need to save that into another variable that you can use like this:
getAllItemsForDisplay: function() {
var obj = this;
$.getJSON('services/act_getAllItems/', function(data) {
$('#items-list').empty();
$('#items-listTmpl').tmpl(data).appendTo('#items-list');
obj.showHideCleanupButton();
BeefyUtils.noSelect();
});
},
To piggy-back on jfriend00's answer, change this:
getAllItemsForDisplay: function() {
$.getJSON('services/act_getAllItems/', function(data) {
$('#items-list').empty();
$('#items-listTmpl').tmpl(data).appendTo('#items-list');
this.showHideCleanupButton();
BeefyUtils.noSelect();
});
},
to this:
getAllItemsForDisplay: function() {
var self = this;
$.getJSON('services/act_getAllItems/', function(data) {
$('#items-list').empty();
$('#items-listTmpl').tmpl(data).appendTo('#items-list');
self.showHideCleanupButton();
BeefyUtils.noSelect();
});
},
This will give you the context that called getAllItemsForDisplay, which I assume is what you want.

Avoiding eval when executing js returned from ajax call

I want to make an ajax call that will return a json object. One of this JSON object's properties will be the string of a function to be executed in the client. I realise this can easily be solved by using eval, but seeing the many disadvantages of eval, I'd rather avoid it. My question is:
Can I in some way return from the server some js code and execute it without resorting to eval?
As requested, here's some example code:
Server (Node.js):
var testFunc = function() {
alert('h1');
};
app.get('/testPack', function(req, res) {
var template = jade.render('h1 hi');
res.send({
template : template,
entity : testFunc.toString(),
data : {
id: "OMG I love this"
}
});
});
Client:
$(document).ready(function() {
$.ajax({
url: '/testPack',
success: function(data) {
$('body').append($(data.template))
alert(data.data.id);
var entity = eval(data.entity);
entity();
}
})
})
Of course, the returned function called entity wouldn't do such a silly thing, it would expose an API of the returned widget.
Just to clarify, I'd like to avoid having to make a separate call for the javascript itself. I'd rather bundle it with the template and data to render.
Easiest way to do that, is not to call a server through an ajax, but instead to create a new script tag on the page with the url pointing to a RESTful web-service that would output pure JavaScript (not JSON). That way your output will be evaluated by the browser directly without the use of eval.
To expand a little on my answer:
To get around the problems of running script in the global context you could do some tricks. For example, when you are adding script tag to the head, you can bind onload event (or rather fake onload event, since IE doesn't support onload on the script tag) to it, and if your response from the server will be always wrapped in the the function with a known name, you could apply that function from within your object. Example code below (this is just an example though):
function test ()
{
this.init = function ()
{
var script = document.createElement("script");
script.type = "text/javascript";
script.language = "javascript";
script.src = "test.js";
var me = this;
window.callMe = function () { me.scriptReady(me); };
var head = document.getElementsByTagName("head")[0];
head.appendChild(script);
};
this.scriptReady = function (object)
{
serverResponse.call(object);
};
this.name = "From inside the object";
this.init();
}
var t=new test();
The server response should look something like this:
function serverResponse()
{
alert(this.name);
}
window.callMe();
In this case, everything inside serverResponse() will use your object as "this". Now if you modify your server response in this way:
function serverResponse()
{
this.serverJSONString = { "testVar1": "1", "testVar2": 2 };
function Test()
{
alert("From the server");
}
Test();
}
window.callMe();
You can have multiple things being returned from the server and with just one response. If you don't like just setting variables, then create a function in your main object to handle JSON string that you can supply by calling this function from your response.
As you can see, it's all doable, it really doesn't look pretty, but then again, what you are trying to do is not pretty to begin with.
P.S. Just inserting a string inside tag will not work for IE, it will not allow you to do that. If you don't have to support IE, then you could get away with just inserting server response inside a newly created script tag and be done with it.
P.P.S. Please don't use this code as is, cause I didn't spend too much time writting it. It's ugly as hell, but was just ment as an example:-)
No, you can't do this by definition, because JavaScript functions are not valid JSON. See the spec here:
http://www.json.org/
If you're returning a string, then that's what it is: just a string. You can't evaluate it without eval. You can call whatever else you're returning whatever you want, but please don't call it JSON.
Here's an example of how I think this could work.
The json object represents what is returned from the server. The c and d properties contain function names as strings. If those functions are properties of some other object which exists in your page, then you should be able to call them using the object["property"] accessor.
See it working on jsFiddle: http://jsfiddle.net/WUY4n/1/
// This function is a child of the window object
window.winScopedFunction = function() {
alert("ROCK THE WIN");
}
// This function is a child of another object
var myObject = {
myFunction : function() {
alert("ROCK ON");
}
};
// pretend that this json object was the result of an ajax call.
var jsonResultFromServer= {
a : 1,
b : 2,
c : "myFunction",
d : "winScopedFunction"
};
// you can call the local functions like so
myObject[jsonResultFromServer.c]();
window[jsonResultFromServer.d]();
Yes, there's a way, but it has the exact same disadvantages as eval.
You can use the Function constructor to create a new function, and then call it. For example:
new Function(code)();
http://code.google.com/p/json-sans-eval/ is a fast JSON parser that does not use eval, and JSON.parse is becoming increasing widely available in new browsers. Both are excellent alternatives to eval for parsing JSON.
You can use the trick that Google does with Google Charts.
<html>
<head>
<script>
function onWorkDone(data) {
console.log(data);
}
</script>
<script src="callback.js"></script>
</head>
</html>
Then your callback.js is:
function doWork(callback) {
callback({result: 'foo'});
}
doWork(onWorkDone);
Basically, your script will call onWorkDone when the doWork completed. You can see a working example here:
http://jsfiddle.net/ea9Gc/
Do you have some example cases? Some things I can think of is you that you can just have a regular function inside your js file, and your server will return some parameters for your function to execute. You can even specify what function to use! (Isn't that amazing?)
// your js file
var some_namespace = {
some_function : function(a, b){
// stuff
}
}
// your server output
{
some_other_data: "123",
execute: {
func: "some_namespace.some_function",
params: [1, 2]
}
}
// your ajax callback
function(r){
window[r.execute.func].apply(this, r.execute.params);
}
The reasons of not using eval
Well, you already said it yourself. Don't use eval. But you have a wrong picture regarding why.
It is not that eval is evil. You are getting the reason wrong. Performance considerations aside, using eval this way allows a sloppy programmer to execute code passed from server on the client. Notice the "passed from server" part.
Why never execute code passed from server
Why don't you want to execute code passed from the server (incidentally that's what you're planning to do)?
When a browser executes a script on a web page, as long as the web site is valid -- i.e. really yours, and not a malware site pretending to be yours trying to trick your users -- you can be reasonably sure that every bit of code the browser is running is written by yourself.
Hacker's heaven -- script injection attacks
Now, if you are passing data from the server to your web application, and that data contains executable functions, you're asking for trouble. In the long, twisted journey of that data going from your server to your client's browser, it goes through the wild west called the Internet, perhaps through multiple layers of proxies and filters and converters, most of which you do not control.
Now, if a hacker is hiding somewhere in the middle, takes your data from the server, modify the code to those functions to something really bad, and sends it away to your client, then your client browser takes the data and executes the code. Voila! Bad things happen. The worse is: you (at the server side) will never know that your clients are hacked.
This is called a "script injection attack" and is a serious sercurity risk.
Therefore, the rule is: Never execute functions returned from a server.
Only pass data from server
If you only accept data from a server, the most that can happen whan a hacker tempers with it is that your client will see strange data coming back, and hopefully your scripts will filter them out or handle them as incorrect data. Your client's browser will not be running any arbitrary code written by the hacker with glee.
In your client-side script, of course you're sticking to the Golden Rule: Do not trust ANY data coming through the Internet. Therefore you'd already be type-check and validating the JSON data before using it, and disallowing anything that looks suspicious.
Don't do it -- pass functions from server and execute on client
So, to make a long story short: DON'T DO IT.
Think of another way to specify pluggable functionalities on the browser -- there are multiple methods.
I've had this same question, and I fixed it this way:
File: functions.js.php?f=1,3
$functions=array(
'showMessage' => 'function(msg){ alert(msg); }',
'confirmAction' => 'function(action){
return confirm("Are you sure you want to "+action+"?");
}',
'getName' => 'function getName(){
return prompt("What is your name?");
}'
);
$queried = explode($_REQUEST['f']);
echo 'var FuncUtils = {'; // begin javascript object
$counter=1;
foreach($functions as $name=>$function){
if(in_array($counter, $queried))
echo '"'.$name.'":,'.$function.',';
$counter++;
}
echo '"dummy":null };'; // end javascript object
File: data5.json
{
"action" : ['confirmAction','exit']
}
File: test.js
$(document).ready(function(){
$.getScript('functions.js.php?f=1,3');
});
function onBeforeExit(){
$.getJSON('data5.json', function(data) {
var func = data.action.shift();
FuncUtils[func].apply(null, data.action);
});
}

Function not defined javascript

For some reason my javascript code is messed up. When run through firebug, I get the error proceedToSecond not defined, but it is defined!
JavaScript:
<script type = "text/javascript">
function proceedToSecond () {
document.getElementById("div1").style.visibility="hidden";
document.getElementById("div2").style.visibility="visible";
}
function reset_Form() {
document.personalInfo.reset();
}
function showList() {
alert("hey");
if (document.getElementsById("favSports").style.visibility=="hidden") {
document.getElementsById("favSports").style.visibility="visible");
}
}
//function showList2() {
//}
</script>
HTML:
<body>
<!--various code -->
<input type="button" onClick="proceedToSecond()" value="Proceed to second form"/>
</body>
The actual problem is with your
showList function.
There is an extra ')' after 'visible'.
Remove that and it will work fine.
function showList()
{
if (document.getElementById("favSports").style.visibility == "hidden")
{
// document.getElementById("favSports").style.visibility = "visible");
// your code
document.getElementById("favSports").style.visibility = "visible";
// corrected code
}
}
There are a couple of things to check:
In FireBug, see if there are any loading errors that would indicate that your script is badly formatted and the functions do not get registered.
You can also try typing "proceedToSecond" into the FireBug console to see if the function gets defined
One thing you may try is removing the space around the #type attribute to the script tag: it should be <script type="text/javascript"> instead of <script type = "text/javascript">
I just went through the same problem. And found out once you have a syntax or any type of error in you javascript, the whole file don't get loaded so you cannot use any of the other functions at all.
important: in this kind of error you should look for simple mistakes in most cases
besides syntax error, I should say once I had same problem and it was because of bad name I have chosen for function. I have never searched for the reason but I remember that I copied another function and change it to use. I add "1" after the name to changed the function name and I got this error.

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