Loading Please Wait...
JSONP is a method for sending JSON data without worrying about cross-domain issues.
JSONP does not use the XMLHttpRequest object.
JSONP uses the <script> tag instead.
JSONP stands for JSON with Padding.
Requesting a file from another domain can cause problems, due to cross-domain policy.
Requesting an external script from another domain does not have this problem.
JSONP uses this advantage, and request files using the script tag instead of the XMLHttpRequest object.
<script src="demo_jsonp.php">
The file on the server wraps the result inside a function call.
<?php
$myJSON = '{ "name":"John", "age":30, "city":"New York" }';
echo "myFunc(".$myJSON.");";
?>
The result returns a call to a function named "myFunc" with the JSON data as a parameter.
Make sure that the function exists on the client.
The function named "myFunc" is located on the client, and ready to handle JSON data.
function myFunc(myObj) {
document.getElementById("demo").innerHTML = myObj.name;
}
The example above will execute the "myFunc" function when the page is loading, based on where you put the script tag, which is not very satisfying.
The script tag should only be created when needed.
The following example create and insert the <script> tag when a button is clicked.
function clickButton() {
let s = document.createElement("script");
s.src = "demo_jsonp.php";
document.body.appendChild(s);
}
The examples above are still very static.
Make the example dynamic by sending JSON to the php file, and let the php file return a JSON object based on the information it gets.
<?php
header("Content-Type: application/json; charset=UTF-8");
$obj = json_decode($_GET["x"], false);
$conn = new mysqli("myServer", "myUser", "myPassword", "Northwind");
$result = $conn->query("SELECT name FROM ".$obj->$table." LIMIT ".$obj->$limit);
$outp = array();
$outp = $result->fetch_all(MYSQLI_ASSOC);
echo "myFunc(".json_encode($outp).")";
?>
The "myFunc" function will be called from the php file:
const obj = { table: "products", limit: 10 };
let s = document.createElement("script");
s.src = "jsonp_demo_db.php?x=" + JSON.stringify(obj);
document.body.appendChild(s);
function myFunc(myObj) {
let txt = "";
for (let x in myObj) {
txt += myObj[x].name + "<br>";
}
document.getElementById("demo").innerHTML = txt;
}
When you have no control over the server file, how do you get the server file to call the correct function?
Sometimes the server file offers a callback function as a parameter.
let s = document.createElement("script");
s.src = "jsonp_demo_db.php?callback=myDisplayFunction";
document.body.appendChild(s);
How you feel about this blog:
Share this blog on:
If you find any error in the turtorials, or want to share your suggestion/feedback, feel free to send us email at: info@lynxsia.com
Contact Us
We are concern with various development process like website design & development, E-commerce development, Software development, Application development, SMS & Bulk SMS Provider, PWA Development, and many more..
Copyright © , Lynxsia IT Solutions, All rights reserved