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How to read variables from Session Storage ?
How to read variables from Session Storage ?
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Android Question WebView DOM storage: how to get access ?
- Thread starter peacemaker
- Start date
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ChatGPT generated these HTML pages to store a page count using various browser storage methods:
Notes:
Session Storage:
Local Storage:
Cookie Storage:
- Session Storage - Only stores values for the current tab session - opening a new tab in the browser will clear values
- Local Storage - Stores data between browser sessions
- Cookie Storage - Stores data in browser cookie with expiration date
B4X:
Sub Process_Globals
Dim WebView1 As WebView
End Sub
Sub Globals
Dim wvExtras As WebViewExtras
End Sub
Sub Activity_Create(FirstTime As Boolean)
Activity.LoadLayout("layout") ' Ensure this matches your layout file name
WebView1.Initialize("WebView1")
Activity.AddView(WebView1, 0, 0, 100%x, 100%y)
wvExtras.Initialize(WebView1)
' Enable JavaScript in the WebView
wvExtras.addJavascriptInterface(WebView1, "B4A")
' Load some initial HTML or a webpage
WebView1.LoadUrl("https://www.example.com")
' Example: Writing to localStorage
wvExtras.ExecuteJavascript("localStorage.setItem('key', 'value');")
' Example: Reading from localStorage
Dim js As String
js = "var value = localStorage.getItem('key'); B4A.CallSub('ProcessValue', value);"
wvExtras.ExecuteJavascript(js)
End Sub
Sub WebView1_PageFinished (Url As String)
' Inject JavaScript here if you need to wait for the page to load
End Sub
' This Sub will be called from JavaScript
Sub ProcessValue(value As String)
Log("Received value from localStorage: " & value)
End SubNotes:
- You might need to use wve.addWebChromeClient(wv, "WVE") to add chromeclient to the webview
- You might need to use WebViewSettings lib to do a wvs.setDOMStorageEnabled(wv,True) to enable DOM storage
Session Storage:
B4X:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Page View Counter</title>
</head>
<body>
<h1>Page View Counter</h1>
<p>Number of times you have visited this page: <span id="viewCount"></span></p>
<script>
// Check if there's already a count stored in session storage
function getPageViews() {
return sessionStorage.getItem('pageViews');
}
// Increment the page view count and store it in session storage
function incrementPageViews() {
let count = getPageViews();
count = count ? parseInt(count) + 1 : 1;
sessionStorage.setItem('pageViews', count);
return count;
}
// Display the current count on the webpage
function displayCount() {
const count = incrementPageViews();
document.getElementById('viewCount').textContent = count;
}
// Call the display function on page load
window.onload = function() {
displayCount();
}
</script>
</body>
</html>Local Storage:
B4X:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Persistent Page View Counter</title>
</head>
<body>
<h1>Persistent Page View Counter</h1>
<p>Number of times you have visited this page: <span id="viewCount"></span></p>
<script>
// Check if there's already a count stored in local storage
function getPageViews() {
return localStorage.getItem('pageViews');
}
// Increment the page view count and store it in local storage
function incrementPageViews() {
let count = getPageViews();
count = count ? parseInt(count) + 1 : 1;
localStorage.setItem('pageViews', count);
return count;
}
// Display the current count on the webpage
function displayCount() {
const count = incrementPageViews();
document.getElementById('viewCount').textContent = count;
}
// Call the display function on page load
window.onload = function() {
displayCount();
}
</script>
</body>
</html>Cookie Storage:
B4X:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Cookie-based Page View Counter</title>
</head>
<body>
<h1>Cookie-based Page View Counter</h1>
<p>Number of times you have visited this page: <span id="viewCount"></span></p>
<script>
// Function to read a cookie value
function getCookie(name) {
let cookieArray = document.cookie.split(';');
for(let i = 0; i < cookieArray.length; i++) {
let cookiePair = cookieArray[i].split('=');
if (name == cookiePair[0].trim()) {
return decodeURIComponent(cookiePair[1]);
}
}
return null;
}
// Function to set a cookie
function setCookie(name, value, daysToExpire) {
const date = new Date();
date.setTime(date.getTime() + (daysToExpire*24*60*60*1000));
const expires = "expires=" + date.toUTCString();
document.cookie = name + "=" + encodeURIComponent(value) + ";" + expires + ";path=/";
}
// Increment the page view count and store it in a cookie
function incrementPageViews() {
let count = getCookie('pageViews');
count = count ? parseInt(count) + 1 : 1;
setCookie('pageViews', count, 7); // Set cookie to expire in 7 days
return count;
}
// Display the current count on the webpage
function displayCount() {
const count = incrementPageViews();
document.getElementById('viewCount').textContent = count;
}
// Call the display function on page load
window.onload = function() {
displayCount();
}
</script>
</body>
</html>
Last edited:
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B4X:
js = "var value = localStorage.getItem('key'); B4A.CallSub('ProcessValue', false, value);"
or
js = "var value = localStorage.getItem('key'); B4A.CallSub('ProcessValue', true, value);"B4A.Callsub (Webviewextras) and javascript (SOLVED)
Hello, Despite much research I did not understand the difference between true and false in the javascript command B4A.CallSub('subInB4a', false, data); and B4A.CallSub('subInB4a', true, data); Thank you so much
www.b4x.com
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