I am using $.post to load some js code from a MYSQL database. How do I execute it?
You can use $.ajax (instead of $.post) with the the dataType option set to script:
"script": Evaluates the response as JavaScript and returns it as plain text. Disables caching unless option "cache" is used. Note: This will turn POSTs into GETs for remote-domain requests.
$.eval = function(str) {
eval(str);
}
$.fn.eval = function(str) {
eval(this.selector);
}
$.post(url, function(data) {
$.eval(data);
//$(data).eval();
});
Jokes aside. You can use eval to run a snippet of JavaScript. I'm sure everyone else will tell you why eval is evil.
Ideally though what your doing is bad. There's a far better way to solve your problem that doesn't involve grabbing code from a database.
Related
I have a problem and hope you can help.
Ii have a status.PHP file containing a js.
STATUS.PHP
<? ..stuff... ?>
<html>
<head>
<title>BCM Status Page</title>
<script src="jquery-3.3.1.min.js"></script>
<script src="updater.js"></script>
</head>
<body bgcolor="#305c57" onload='init();'>
As you can see in the html ihave included a JS, during "onload" i'm calling the init() function of the javascript called updater.js
Now in the UPDATER.JS
function init() {
setInterval(read, 2000)
}
function read() {
$.ajax({
type: 'POST',
url: 'readDB.php',
dataType: 'jsonp',
success: function (data) {
console.log(data);
var json_obj = $.parseJSON(data);
console.log(json_obj[0].gwnumber);
},
error: function () {
console.log("Error loading data");
}
});
}
I'm doing an ajax call to the readDB.php that is working as intended, infact i have the correct value in the json_obj.
My question is: how can i get the json_obj value and pass it to the status.PHP file that is the one who's including the JS too?
Hope you can help. TY
Ok, there is a lot to say in this argument, but i will be the briefiest possible.
first things first
php and Javascript are two different programming language with a completely different paradigm.
The first is a back-end focused programming language;
Javascript instead is more front-end focused, just for entirety i have to mention that JS is used also for the backend part with a special eviroment called Node.js
back to the problem, the things that you are trying to do is not impossible but is excactly as you asked, your're idea (if i got it) was to pass the data from the js to the php like a parameter in a function...
the thing is that the php is elaborate and renderizated before in the server and the javascript is executed in the client, in the client web page there is no more footprint the php. This process is described very well at this link: http://php.net/manual/en/intro-whatis.php
The possible solution is:
FRONT-END(js): make another ajax call(request) to the same page that you are displaying with all the data that you want to elaborate.
BACK-END(php): controll if this request has been made, then access the data with the global variables $_POST & $_GET (depending on the type of the request), then elaborate this data.
if I can I suggest you to make a check if the manipulation that you want to do on those data need to be done in the server-side and not by the js!
Consider the order of execution:
User visits status.php
Browser requests status.php
Server executes status.php and sends response to browser
JS requests readDB.php
Browser requests readDB.php
Server executes readDB.php and sends response to browser
JS processes response
Go To 4
By the time you get to 7, it is too late to influence what happens at step 2.
You could make a new Ajax request to status.php and process the response in JS, but since status.php returns an entire HTML document, that doesn't make sense.
You could use location to load a new page using a URL that includes status.php and a query string with information from the Ajax response, but that would making using Ajax in the first place pointless.
You should probably change readDB.php to return *all** the data you need, and then using DOM methods (or jQuery wrappers around them) to modify the page the user is already looking at.
The simpliest and fastest (maybe not the sexiest way) to do it :
create global variable var respondData; in STATUS.PHP
within you ajax request on success function assign your data callback to it
respondData = data;
Now you have an access to it from every place in your code even when the ajax request is done. Just bare in mind to ensure you will try to access this variable after the page will fully load and after ajax will process the request. Otherwise you will get 'undefined'
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'm quite a beginner in JS and even more in jQuery UI. I don't understand if my problem has a very simple synchronous solution, or if I need to write callback functions to cope with something that cannot be anything else than asynchronous...
I had this in a script associated with an HTML document:
var json = "[{ ... some object ... }]"
As the JSON object must be changed, I've created a text file and moved the value into it. Now I've to read the value from the file to assign it to the variable.
I see that when in production, the HTML page will be served by an HTTP server, and the file must be remotely retrieved using HTTP on the server. But also that if I want to test the page on my development machine, with no server, this is just reading a local file.
Is there a single piece of code that can read the JSON value in both situation, in a synchronous mode, so that something like this would be possible:
var json = ... piece of code...
I initially thought using:
$.getJSON("file.json", function(obj) { json = obj; });
expecting a read error would lead to json variable being the empty or null, but it seems the call is asynchronous and requires more code in callback functions.
Any guidance appreciated.
First of all, the call definitely should be synchronous. Just move the rest of your code into the callback, it's not that hard - and it will make your browser responsive while the file is downloaded.
If this is really a big problem, you can use the async option in $.ajax:
$.ajax({
async: false,
url: 'file.json',
dataType: 'json',
success: function (value) { json = value; }
});
Note: This will only work if the file you're requesting is from the same domain, and may or may not fail for local files, depending on the browser.
Here's some simple Javascript:
(function($){
var ajax_callback = function(data) { window.location.hash = data.h1; };
$('.clickable').live('click', function() {
$.post('server.fcgi', {}, ajax_callback, 'json');
}
);
})(jQuery);
The server is a c++ binary (yes, i know) that spits out (through fast_cgi) the string:
{"h1":"newhash"}.
The expected behavior is that the URL should change.
Instead, nothing happens and Firebug complains that 'data' is "null"!.
Any help would be greatly appreciated!
Will.
When the following code enters "ajax_callback", it says that "data" is "null"!.
But the server is a c++ binary that is confirmed to return the JSON string {"h1":"newhash"}.
Anyone have an idea why JQuery seems unable to accept the JSON data when calling the ajax_callback?
I did have similar problem as you have mentioned when using $.POST().
There are two things if you are using jquery $.post method. You need to add an extra bracket before defined data type ("JSON") as shown below. I don't know why but it works, it will return data.
$.post('server.fcgi', {}, ajax_callback,{}, 'json');
The second thing is that you will need to parse JSON data using $.parseJSON(data) in side the callback function.
One more thing to make sure that the url to fetch JSON, the page document type should be defined as JSON in the header.
I have given an example below.
$.post("url/path/here/to/json", {}, function(data){
if(data){ // just in case the called program had a problem
var obj = $.parseJSON(data);
.... do everything else using the Obj->
}
},{},"json");
This will work.
However I recommend to you to use another Jquery function specially implemented for JSON, that is called
$.getJSON();
Here is the url for more information
And I am suggesting you to use the following method instead of the one described by you.
$(document).ready(function(){
$('.clickable').live('click', function() {
$.getJSON('server.fcgi', function(data){
window.location.hash = data.h1;
});
}
);
});
Make sure the server also returns the correct HTTP headers before the payload. E.g.:
HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: ...
...
{"h1":"bla"}
From your description, I could not quite make out if all it did was printf("{\"h1\":\"bla\"}"); or not.
To check the actual result, use a command line tool like HEAD, GET, wget, curl, or even nc. If you are not able to use one of those, you might get some clues from the Net panel in Firebug and the like.
Probably not the answer you want to hear, but I assume you're using jQuery 1.4.2? I noticed that this does work as expected in 1.3.2 so you might want to consider using that instead. :(
For example:
#!/usr/bin/python
print "This is python."
print "<script type="text/javascript">
var pass_to_python = new Number(7)
</script>"
the_number = pass_to_python???
How do I get the pass_to_python in python?
With pyv8 you can execute javascript from within Python.
import PyV8
class Global(PyV8.JSClass):
pass
with PyV8.JSContext(Global()) as ctxt:
the_number = ctxt.eval("var pass_to_python = new Number(7)")
see http://code.google.com/p/pyv8/
You can GET or POST to the Python script. If you need to do this dynamically, you can use AJAX.
Here is a good link: How are POST and GET variables handled in Python?
i am using flask and ajax to pass values from javacript to python
function pass_values() {
var pass_to_python = new Number(7)
$.ajax(
{
type:'POST',
contentType:'application/json;charset-utf-08',
dataType:'json',
url:'http://127.0.0.1:5000/pass_val?value='+pass_to_python ,
success:function (data) {
var reply=data.reply;
if (reply=="success")
{
return;
}
else
{
alert("some error ocured in session agent")
}
}
}
);
}
python:
#app.route('/pass_val',methods=['POST'])
def pass_val():
name=request.args.get('value')
print('name',name)
return jsonify({'reply':'success'})
HTTP is a simple request-response protocol, it doesn't let you pause mid-stream and wait for more information from the client — and since your JS runs in the browser (JS can run on the server, but most people wouldn't be attempting this if they didn't need the code to run in the browser, so I'm assuming that using server side JS is out of the question) and the Python runs on the server, that is what you need for your code to work (as well as fixing your broken quote nesting in the Python code).
You need to load the complete document, and then issue a new HTTP request.
This might involve having the JS set location.href (making sure you have a fallback for non-JS clients), it might involve using XMLHttpRequest to load new data asynchronously, it might be best using another technique (it is hard to say for sure as your example simplifies too much to tell what X is)
I think using JSON is the best way.you can create a JSON file as intermidiary between JavaScript and Python, both languages can access and modify JSON file