Develop Reference

how to consume data from response.write

I am opening an html page with the code below. I am also sending is data to that page with the response.write() function:
fs.readFile('./calc.html', function(error, data){
if(error){
//do nothing for now
} else if (data){
resp.writeHead(200, {'Content-Type':'text/html'});
var sum = 9;
resp.write(sum);
resp.end(data);
}
});
How do I consume the value from 'sum' in calc.html when the page opens? In the script tag in the , I'm utilizing the Window.onload method to perform an action when the page loads. The number 9 appears in the top left hand corner of the web page when it loads, so I konw it's there, I just dont know how to consume it and use it.
<script type="text/javascript">
var htmlSum = 0;
function fetchData() {
htmlSum = //How to I scrape the 'sum' variable sent into the page?????
}
window.onload = fetchData;
</script>

What you're writing here gets received as an HTML page (in this case), which is why it just displays the number "9" in the browser. If you package it inside a <script> tag it will be available as JS:
resp.writeHead(200, {'Content-Type':'text/html'});
var sum = 9;
resp.write('<script type="text/javascript">var mySumVar = ' + sum + ';</script>');
return resp.end(data); //the "return" doesn't change anything,
//but it's good practice to make sure the function ends here
...And you can then access mySumVar from your other clientside scripts. Note that this will go in the global scope, which makes it easier to access but also bad practice. You may want to package it inside some other object to avoid polluting the scope.

Instead of writing the number at the top of the page, you can write placeholders that will be replaced with your data. For example, you could use {{sum}} as a placeholder and replace {{sum}} with your sum:
fs.readFile('./calc.html', function(error, data){
if(error){
//do nothing for now
} else if (data){
resp.writeHead(200, {'Content-Type':'text/html'});
var sum = 9;
resp.end(data.replace("{{sum}}", sum);
}
});
and in your html..
<script type="text/javascript">
var number = 0;
function fetchData() {
number = {{sum}};
}
window.onload = fetchData;
</script>
If you are planning to include more logic from the serverside into your webpage, I would recommend you look into a template engine such as EJS.

How get information from variable web page with use node.js?

There is a web page. In page source have script:
<script>
var important = [{....}];
</script>
How get information from this variable with use node.js???
In a similar situation, when information was in function:
$(function() {
_very.important ([{....}]);
I use code:
var cloudscraper = require("cloudscraper");
cloudscraper.get("link" , function(error, response, data) {
if (error) {
console.log('ERRRRRRROR');
} else {
var info = JSON.parse(data.split("_very.important(")[1].split(")")[0]);
But, I dont know how work with this problem.
var important = [{....}];

You can assign a id to the script like <script id="script"> and get the details through innerHTML like
document.getElementById('script').innerHTML

passing data using post array in java-script

i am try to load B.php from A.php after execution in the function and pass some data using a post array from A.php to B.php within same time.
code list as follows
A.php
<script type="text/javascript">
alert_for_the_fucntion();
window.location.href = "B.php";
function alert_for_the_fucntion() {
$.post("B.php", {action: 'test'});
}
</script>
B.php
<?php
if (array_key_exists("action", $_POST)) {
if ($_POST['action'] == 'test') {
echo 'ok';
}
}
?>
for testing purpose i tried to echo something in the B.php. but currently this is not working. have i done any mistakes? or is there any possible method to do this.

Your code does this:
Tells the browser to navigate to B.php (using a GET request)
Triggers a POST request using XMLHttpRequest
The POST request probably gets canceled because the browser immediately leaves the page (and the XHR request is asynchronous). If it doesn't, then the response is ignored. Either way, it has no effect.
You then see the result of the GET request (which, obviously, doesn't include $_POST['action']) displayed in the browser window.
If you want to programmatically generate a POST request and display the result as a new page then you need to submit a form.
Don't use location. Don't use XMLHttpRequest (or anything that wraps around it, like $.ajax).
var f = document.createElement("form");
f.method = "POST";
f.action = "B.php";
var i = document.createElement("input");
i.type = "hidden";
i.name = "action";
i.value = "test";
f.appendChild(i);
document.body.appendChild(f);
f.submit();
If you want to process the results in JavaScript then:
Don't navigate to a different page (remove the line using `location)
Add a done handler to the Ajax code
e.g.
$.post("B.php", {action: 'test'}).done(process_response);
function process_response(data) {
document.body.appendChild(
document.createTextNode(data)
);
}

Try this:
Javascript:
<script type="text/javascript">
window.onload = alert_for_the_fucntion;
function alert_for_the_fucntion() {
$.post("B.php",
{
action: 'test'
},
function(data, status){
if(status=="success"){
alert(data);
}
}
);
}
</script>
PHP
<?php
if(isset($_POST['action'])){
echo $_POST['action'];
}
?>

Flaskr url_for with javascript variable as parameters is not working to python

I'm trying to use flask with url_for. The problem is that when I try to launch an alert with the value of the javascript variable everything seems ok, but when I try to launch a alert with the url_for the content of the variable is not printed. What I'm doing wrong? or What is missing in my code?
How can I pass a JavaScript variable into the url_for function?
html code:
<a class="dissable_user_btn" data-user_id="{{user.id}}" href="#" title="Change Status"><i class="fa fa-plug"></i>
</a>
JS Code:
<script type="text/javascript">
$(document).ready(function(){
$('.dissable_user_btn').click(function( event ) {
var user_id = $(this).data("user_id")
alert(user_id) //everything ok
alert ('{{url_for('.dissable', _id=user_id)}}'); //dont print the valur of user_id
</script>

Short answer: you can't. Flask & Jinja2 render the template on the server side (e.g. Flask is translating all of the {{ }} stuff before it sends the HTML to the web browser).
For a URL like this where you're including a variable as part of the path you'd need to build this manually in javascript. If this is an XHR endpoint I'd recommend using GET/POST to transfer the values to the server as a better best practice than constructing the URL this way. This way you can use Jinja:
$(document).ready(function(){
var baseUrl = "{{ url_for('disable') }}";
$('.dissable_user_btn').click(function(event) {
var user_id = $(this).data("user_id");
// first part = url to send data
// second part = info to send as query string (url?user=user_id)
// third parameter = function to handle response from server
$.getJSON(baseUrl, {user: user_id}, function(response) {
console.log(response);
});
});
});

I found another solution for this. My problem started when I needed to pass a variable with space.
First I created a function to remove trailing and leading spaces
function strip(str) {
return str.replace(/^\s+|\s+$/g, '');}
After that, I used the function and encoded the URL
<script type="text/javascript">
$(document).ready(function(){
$('.dissable_user_btn').click(function( event ) {
var user_id = $(this).data("user_id")
alert(user_id)
user_id = strip(user_id).replace(" ","%20");
alert ('{{url_for('.dissable', _id='user_id')}}.replace('user_id',user_id);
</script>
It worked pretty nice for me!
This is how I applied to my problem
<script>
function strip(str) {
return str.replace(/^\s+|\s+$/g, '');}
$(document).ready(function() {
$('#exportcountry').click(function() {
var elemento = document.getElementById("countryexportbtn");
var country = strip(elemento.textContent).replace(" ","%20");
$('#exportevent').load("{{ url_for('get_events',country = 'pais') }}".replace('pais',country));
});
});
</script>

Post Javascript to PHP and then retrieve in another javascript

I m trying to post the value from my java_post.js into php_post.php and then retrieve in another javascript page, index.html. So far i can post the value into the php_post.php and retrieve back into my java_post.js as alert(data)
but i cannot retrieve from my index.html
Java_post.js
var url_link ="index.html";
//On Click Select Function
$("#table_hot").on('click', 'tbody tr',function(){
$(this).addClass('selected').siblings().removeClass('selected');
var value=$(this).find('td:first').html();
$.post('PHP_post/php_post.php',
{
postvalue:value
},
function(data){
alert(data);
}
);
});
//Window Pop Out Function
function hotspot_pop(url_link){
newwindow = window.open(url_link, '', "status=yes,
height=500; width=500; resizeable=no");
}
The value is retrieve when the client click the selected table and then post into the php_post.php. The php_post.php will filter the result and return to index.html.
$filtered_students = array_filter($ARRAY, function($row) {
$hotspot_value = $_POST['postvalue'];
if($row['name'] == $hotspot_value){
return true;
}
});
echo $filtered_students;
So now i m able to retrieve the value and post into as an alert for my java_post.js but the value is no pass into index.html and i receive the error for undefined postvalue.
<html>
<script src="js/jquery-1.11.1.min.js"></script>
<body>
<div id="result"></div>
<script>
var xmlhttp_user = new XMLHttpRequest();
var url_user = "PHP_post/php_post.php";
xmlhttp_user.onreadystatechange=function() {
if (xmlhttp_user.readyState == 4 && xmlhttp_user.status == 200) {
document.getElementById("result").innerHTML=xmlhttp_user.responseText; }
}
xmlhttp_user.open("GET", url_user, true);
xmlhttp_user.send();
</script>
</body>
</html>
So my problem is now, is there any method that allow me to show the value in index.html from php_post.php. As a reminder the alert(data) from java_post.js is just a testing purpose to show the value did post and return from php_post.php

The issue you're having is that when you pass the data into your PHP file and receive the data back in your JavaScript, the information only lasts as long as your current request.
To fix this issue, consider using PHP Session variables to store your data, so that you can retrieve it later.
Example:
// php_post.php
<?php
start_session(); // initializes session for persistent data
$filtered_students = array_filter($ARRAY, function($row) {
$hotspot_value = $_POST['postvalue'];
if($row['name'] == $hotspot_value){
return true;
}
});
$_SESSION["filtered_students"] = $filtered_students; // You can now retrieve this in
// Another PHP file
?>
Now in another file (you would switch your HTML file to get from php_get.php):
//php_get.php
<?php
start_session(); // Don't forget to start the session
echo $_SESSION['filtered_students'];
?>
More information here: http://www.w3schools.com/php/php_sessions.asp

You can set the desired value into PHP session while at php_post.php.
This way, you can retrieve the session's value on any page you desire.