I am trying to read the post request parameters from my HTML. I can read the get request parameters using the following code in JavaScript.
$wnd.location.search
But it does not work for post request. Can anyone tell me how to read the post request parameter values in my HTML using JavaScript?
POST data is data that is handled server side. And Javascript is on client side. So there is no way you can read a post data using JavaScript.
A little piece of PHP to get the server to populate a JavaScript variable is quick and easy:
var my_javascript_variable = <?php echo json_encode($_POST['my_post'] ?? null) ?>;
Then just access the JavaScript variable in the normal way.
Note there is no guarantee any given data or kind of data will be posted unless you check - all input fields are suggestions, not guarantees.
JavaScript is a client-side scripting language, which means all of the code is executed on the web user's machine. The POST variables, on the other hand, go to the server and reside there. Browsers do not provide those variables to the JavaScript environment, nor should any developer expect them to magically be there.
Since the browser disallows JavaScript from accessing POST data, it's pretty much impossible to read the POST variables without an outside actor like PHP echoing the POST values into a script variable or an extension/addon that captures the POST values in transit. The GET variables are available via a workaround because they're in the URL which can be parsed by the client machine.
Use sessionStorage!
$(function(){
$('form').submit{
document.sessionStorage["form-data"] = $('this').serialize();
document.location.href = 'another-page.html';
}
});
At another-page.html:
var formData = document.sessionStorage["form-data"];
Reference link - https://developer.mozilla.org/en-US/docs/Web/API/Window/sessionStorage
Why not use localStorage or any other way to set the value that you
would like to pass?
That way you have access to it from anywhere!
By anywhere I mean within the given domain/context
If you're working with a Java / REST API, a workaround is easy. In the JSP page you can do the following:
<%
String action = request.getParameter("action");
String postData = request.getParameter("dataInput");
%>
<script>
var doAction = "<% out.print(action); %>";
var postData = "<% out.print(postData); %>";
window.alert(doAction + " " + postData);
</script>
You can read the post request parameter with jQuery-PostCapture(#ssut/jQuery-PostCapture).
PostCapture plugin is consisted of some tricks.
When you are click the submit button, the onsubmit event will be dispatched.
At the time, PostCapture will be serialize form data and save to html5 localStorage(if available) or cookie storage.
I have a simple code to make it:
In your index.php :
<input id="first_post_data" type="hidden" value="<?= $_POST['first_param']; ?>"/>
In your main.js :
let my_first_post_param = $("#first_post_data").val();
So when you will include main.js in index.php (<script type="text/javascript" src="./main.js"></script>) you could get the value of your hidden input which contains your post data.
POST is what browser sends from client(your broswer) to the web server. Post data is send to server via http headers, and it is available only at the server end or in between the path (example: a proxy server) from client (your browser) to web-server. So it cannot be handled from client side scripts like JavaScript. You need to handle it via server side scripts like CGI, PHP, Java etc. If you still need to write in JavaScript you need to have a web-server which understands and executes JavaScript in your server like Node.js
<script>
<?php
if($_POST) { // Check to make sure params have been sent via POST
foreach($_POST as $field => $value) { // Go through each POST param and output as JavaScript variable
$val = json_encode($value); // Escape value
$vars .= "var $field = $val;\n";
}
echo "<script>\n$vars</script>\n";
}
?>
</script>
Or use it to put them in an dictionary that a function could retrieve:
<script>
<?php
if($_POST) {
$vars = array();
foreach($_POST as $field => $value) {
array_push($vars,"$field:".json_encode($value)); // Push to $vars array so we can just implode() it, escape value
}
echo "<script>var post = {".implode(", ",$vars)."}</script>\n"; // Implode array, javascript will interpret as dictionary
}
?>
</script>
Then in JavaScript:
var myText = post['text'];
// Or use a function instead if you want to do stuff to it first
function Post(variable) {
// do stuff to variable before returning...
var thisVar = post[variable];
return thisVar;
}
This is just an example and shouldn't be used for any sensitive data like a password, etc. The POST method exists for a reason; to send data securely to the backend, so that would defeat the purpose.
But if you just need a bunch of non-sensitive form data to go to your next page without /page?blah=value&bleh=value&blahbleh=value in your url, this would make for a cleaner url and your JavaScript can immediately interact with your POST data.
You can 'json_encode' to first encode your post variables via PHP.
Then create a JS object (array) from the JSON encoded post variables.
Then use a JavaScript loop to manipulate those variables... Like - in this example below - to populate an HTML form form:
<script>
<?php $post_vars_json_encode = json_encode($this->input->post()); ?>
// SET POST VALUES OBJECT/ARRAY
var post_value_Arr = <?php echo $post_vars_json_encode; ?>;// creates a JS object with your post variables
console.log(post_value_Arr);
// POPULATE FIELDS BASED ON POST VALUES
for(var key in post_value_Arr){// Loop post variables array
if(document.getElementById(key)){// Field Exists
console.log("found post_value_Arr key form field = "+key);
document.getElementById(key).value = post_value_Arr[key];
}
}
</script>
function getParameterByName(name, url) {
if (!url) url = window.location.href;
name = name.replace(/[\[\]]/g, "\\$&");
var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
results = regex.exec(url);
if (!results) return null;
if (!results[2]) return '';
return decodeURIComponent(results[2].replace(/\+/g, " "));
}
var formObj = document.getElementById("pageID");
formObj.response_order_id.value = getParameterByName("name");
One option is to set a cookie in PHP.
For example: a cookie named invalid with the value of $invalid expiring in 1 day:
setcookie('invalid', $invalid, time() + 60 * 60 * 24);
Then read it back out in JS (using the JS Cookie plugin):
var invalid = Cookies.get('invalid');
if(invalid !== undefined) {
Cookies.remove('invalid');
}
You can now access the value from the invalid variable in JavaScript.
It depends of what you define as JavaScript. Nowdays we actually have JS at server side programs such as NodeJS. It is exacly the same JavaScript that you code in your browser, exept as a server language.
So you can do something like this: (Code by Casey Chu: https://stackoverflow.com/a/4310087/5698805)
var qs = require('querystring');
function (request, response) {
if (request.method == 'POST') {
var body = '';
request.on('data', function (data) {
body += data;
// Too much POST data, kill the connection!
// 1e6 === 1 * Math.pow(10, 6) === 1 * 1000000 ~~~ 1MB
if (body.length > 1e6)
request.connection.destroy();
});
request.on('end', function () {
var post = qs.parse(body);
// use post['blah'], etc.
});
}
}
And therefrom use post['key'] = newVal; etc...
POST variables are only available to the browser if that same browser sent them in the first place. If another website form submits via POST to another URL, the browser will not see the POST data come in.
SITE A: has a form submit to an external URL (site B) using POST
SITE B: will receive the visitor but with only GET variables
$(function(){
$('form').sumbit{
$('this').serialize();
}
});
In jQuery, the above code would give you the URL string with POST parameters in the URL.
It's not impossible to extract the POST parameters.
To use jQuery, you need to include the jQuery library. Use the following for that:
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js" type="text/javascript"></script>
We can collect the form params submitted using POST with using serialize concept.
Try this:
$('form').serialize();
Just enclose it alert, it displays all the parameters including hidden.
<head><script>var xxx = ${params.xxx}</script></head>
Using EL expression ${param.xxx} in <head> to get params from a post method, and make sure the js file is included after <head> so that you can handle a param like 'xxx' directly in your js file.
First of all here's my .json file:
{
"ids": [1,2],
"names": ["John Richards", "Doe Williams"],
"skills": [ "Senior Software Engineer", "Junior Software Developer"]
}
And here's my ajax call to display each name from the object.
$.ajax({
dataType: "json",
url: "entries.json",
success: function(data){
for (var i = 0; i < data.names.length; i++){
console.log(data.names[i]);
}
}
});
I have a form with 3 fields and a button which I'm using to submit new data. The problem is that I can't modify that json file and submit that data.
$("#add").on("click",function(){
var url = "entries.json";
//Form input
var id = $("#empID").val();
var fullName = $("#empFullName").val();
var prof = $("#empProf").val();
var entry = { "ids":id,
"names":fullName,
"skills":prof
};
....
Ajax call for modification of the json file?!?!
What I mean by modify is to basically insert the id, fullName and prof into the corresponding field of the json and save it with the new values appended. Any insight? I'm stuck. Pulling is fine. How do I push data to the .json file? If I missed to provide anything important please let me know. I'm relatively new working with ajax.
Thanks in advance!
P.S:I've already made the project using a database if anyone's wondering.
You cannot write to a JSON file using only JavaScript in the browser. But with JavaScript in the browser you can write Document.cookie and also write in the Window.localStorage.
Writing in the localStorage of the browser:
// Form input
var id = $("#empID").val();
var fullName = $("#empFullName").val();
var prof = $("#empProf").val();
var obj = {
"ids": id,
"names": fullName,
"skills": prof
};
localStorage.setItem('myJavaScriptObject', JSON.stringify(obj));
And than to retrieve the object, from the localStorage, you can do:
var obj = JSON.parse(localStorage.getItem('myJavaScriptObject'))
Other thing you can do is to create a service in the backend with a server-side technology like: NodeJS, Ruby on Rails, PHP, JAVA, etc... to handle the writing data in the JSON file.
And then from the browser, making a POST request that sends the form inputs data to the endpoint of your service, the data can be saved into the JSON file.
Hope this can help.
So I have a form, I took the contents of its inputs, threw them into an array, had it made into a JSON and then sent it to PHP so it can in turn decode and enter it into a database. I know it'd be easier to just use a <form method="POST" action="phpfile.php"> but I can't have this redirecting to another page, especially since my PHP is not embedded into HTML, instead it handles things offsite. Otherwise it'd be simpler to just use $_POST["name"] to get what I need. Nonetheless, this page in particular is supposed to create the user, receive a server response, that the user has been entered into the database and then is given an alert with a button to be redirected to the main page.
So anyway here are the relevant sections of this whole process.
JavaScript:
window.onload = function findSubmitButton() {
var button = document.querySelector(".send_info").addEventListener("click", serverInteraction);
}
function serverInteraction() {
var xmlhttp;
var inputArray;
var finalArray = [];
var JSONArray;
if (window.XMLHttpRequest){
xmlhttp = new XMLHttpRequest();
} else if (window.ActiveXObject) {
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
} else {
throw new Error("Your browser is not compatible with XMLHTTP");
return false;
}
inputArray = document.querySelectorAll("input[type=text]");
for(var i = 0; i < inputArray.length; i++){
finalArray[i] = inputArray[i].value;
}
console.log(finalArray);
JSONArray = JSON.stringify({finalArray: finalArray});
console.log(JSONArray);
xmlhttp.open("POST","phpFiles/sendUserInfo.php", true);
xmlhttp.setRequestHeader("Content-type","application/json");
xmlhttp.send(JSONArray);
}
PHP:
<?php
$finalArray = json_decode($_POST['finalArray']);
var_dump($finalArray);
?>
That var_dump simply returns a null and using echo gives me nothing, except a warning that my array variable isn't initialized through XDebug. I'm not quite sure what I'm doing wrong here, I've been following this just like the tutorials tell you to do it, and isn't generating the array. I've also tried $_POST['JSONArray']without any luck in case that was how it was supposed to go. Also tried file_get_contents('php://input') which sends an empty string as well.
You can't get your data from $_POST if you put JSON in your post body.
see this question Receive JSON POST with PHP. php can't handle application/json properly.
For your var_dump is empty, try this
var_dump(file_get_contents('php://input'));
var_dump(json_decode(file_get_contents('php://input'), true));
you will see your data.
And if you send your data without change it to JSON, you will get wrong data.
eg: your finalArray is ['a','b','c'] and you send it directly.
var_dump(file_get_contents('php://input'));
you will see php got string a,b,c instead of ['a','b','c']
So if you want to use $_POST to receive data, you need to use application/x-www-form-urlencoded. you can use jquery to do it. see http://api.jquery.com/jquery.ajax/
$.ajax({
method: "POST",
url: "some.php",
data: { name: "John", location: "Boston" }
})
.done(function( msg ) {
alert( "Data Saved: " + msg );
});
it will serialize your js object into x-www-form-urlencoded and php will handle it properly.
use chrome's dev tools, switch to network and see the request payload and response would be helpful for you.
You are bypassing $_POST by sending the the data as "Content-type","application/json" .
The data will instead be set in the body of request and can be retrieved using file_get_contents("php://input")
For further discussion see file_get_contents("php://input") or $HTTP_RAW_POST_DATA, which one is better to get the body of JSON request?
Generally there is no need to send your data as json to php
I want to go back to previous JSP page with all its value retained on click of previous button in present JSP page. I am using history.back() in JS, but not able to retain the previous field value. How to retain the field values of the previous page?
I would suggest using JQuery and a server side session variable to store the values.
make sure you have an html id on each form element you need to keep
on unload, loop though the elements and send them over to the server to be saved
$(window).unload(function() {
var formValues = {}
//get the form elements
elements.each(function() {
var fieldID = $(this).attr("id");
formValues[fieldID] = $(this).val();
}
json_form = JSON.stringify(formValues);
$.post("/save_form_values/", {form : json_form} );
I haven't included any code for storing on the server (I found it pretty straightforward with django / python).
make another ajax call when you reload the page
$(document).ready(function() {
$.get("/get_form_values/", function(data) {
var formValues = JSON.parse(data);
$.each(formValues, function(fieldID, value) {
id_selector = '#' + fieldID;
$(id_selector).val(value);
}
}
}
I want write a page that returns nothing but reads the parameters posted to it and manipulate them (via JavaScript) before similarly posting to third party's page. Anything returned from the third party will be dropped on the floor. Basically, I'm looking to create a proxy. My 'middle' page will need to run JavaScript. The end page will post to the middle page but not leave the page or report the status of the post.
You'll need to pass the values to your proxy using the GET form method and use window.location.search to get the values (this will only work with simple values, not file uploads).
var qsParm = new Array();
function qs() {
var query = window.location.search.substring(1);
var parms = query.split('&');
for (var i=0; i<parms.length; i++) {
var pos = parms[i].indexOf('=');
if (pos > 0) {
var key = parms[i].substring(0,pos);
var val = parms[i].substring(pos+1);
qsParm[key] = val;
}
}
}
javascript.about.com article on query passing
To resend you'll need to create and populate a form and them call the submit() method on the form element.