How to redirect to a html page from a javascript snippet?
Question
I am new to javascript. I want that when a user enters the username at the time of signup and that name already exists in the database,then i will show a prompt that Name already exists . and you need to enter another username.
Now i want to have a button in the same prompt box clicking on which, the user will be redirected to the Signup page signup.html again.
I am unable to figure out how to do this. What i have done is this---
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<script>
prompt("Username already exists\n please enter another username");
</script>
</body>
</html>
3 answers
solution1
3 ACCPTED 2016-06-11 15:31:58
https://developer.mozilla.org/en-US/docs/Web/API/Window/location
you can put it in any js-script block you like. eg
<script>
function redirectMe(url){
window.location = url;
}
setTimeout(redirectMe('http://stackoverflow.com'}, 3000);
</script>
will redirect to stackoverflow after 3000ms (=3s)
solution2
1 2016-06-11 15:37:55
solution3
1 2016-06-11 15:51:26
To check if a user already exists in a database, you will have to make some server-side code, not only javascript (client-side).
You have to use AJAX to make a call to a server script (in PHP or ASP for example), sending the name entered by the user. The server-side script will check by making a SQL query to check in the DB, and return its response to your javascript if yes or not the user already exists.
Here is an example using jQuery :
HTML
Your name : <input type="text" id="username" />
<button id="myButton" value="check if user exists" />
JAVASCRIPT
<script src="https://code.jquery.com/jquery-2.1.3.min.js" type="text/javascript"></script>
<script>
$(function () {
//when you will click on your button
$('#myButton').click(function(){
//get prompted username
var username = $('#username').val();
//check if username exists making AJAX call
checkUserName(username);
});
});
function checkUserName(name)
{
//ajax call to your server-side script
$.ajax({
url: 'myscript.php',
type: 'POST',
data: 'username='+name,
success: function (response) {
//if response is 1, a user with this name already exists
if(response == 1)
{
alert('user already exists');
}
//the name is available
else
{
//redirect to your "signup.html" page
window.location.href="signup.html"
alert('name is available');
}
}
});
}
</script>
PHP
myscript.php
<?php
//you have to secure and check the variable, depending what you will use, mysqli_real_escape_string, or escape properly the received variables
$username = $_POST['username'];
//query example, you have to ajust depending on your database & user table
$sql = 'SELECT COUNT(username) FROM db.user WHERE username = "'.$username.'"';
//exec your query
//if the count returned result is > 0, there is a user with this name, return 1 for example
//else, user with this name does not exist, return 0 for example
if($return == 1)
echo "1";
else
echo "0";
exit;
Here is the main idea :) try to make a JSFiddle code and try in it, and write here if you have some more problems !
Regards,
Julien
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