How to manipulate HTML in Flutter webview?

Question

I am load website with Flutter webview. But I want replace HTML element when it load. For example:

<span class="name">Replace text</span>

How to do?

Solution

So, it depends what library you are using to load your webview.

I have had some good success using webview_flutter_plus (https://pub.dev/packages/webview_flutter_plus).

With this, you just need to wait for your html to load and inject some javascript to modify whatever html you want.

Like this:

Widget build(BuildContext context) {
    return WebViewPlus(
        initialUrl: myUrl,
        javascriptMode: JavascriptMode.unrestricted,
        onWebViewCreated: (WebViewPlusController webViewController) {
            _webViewController = webViewController;
        },
        onPageFinished: (String url) {
            _webViewController.evaluateJavascript('document.querySelector(".name").innerHTML = "new text";');
        }
   }
}

Comments

[IronMan]

Hi, you could attach a handler to the load event document.addEventListener("DOMContentLoaded", function() { // do my replacement });

[FlutterFirebase]

@IronMan How to do with Flutter webview?

[kikicoder]

dear @Didier Prophete I using this way but it seems evaluating jave script takes too long what I could done about that

[Didier Prophete]

Yeah. The truth is that binging up a webview inside a native app in flutter does take some time (like half a second). After that I think the js evaluation is fine but that initial time is a giant pain. Not sure there is much we can do there until flutter itself improves the webview perf (and there as well, I am not sure flutter can do anything. It might just be that a webview is an expensive class to instanciate...)

[kikicoder]

Dear is there a way I could manage to not showing the webview until it evaluate, I mean the evaluation happens on onpagefinished callback and that it self need some time to be fired

[Didier Prophete]

yes @kikicoder, that's exactly what I do in my own code. I basically hide the webview (I put it in a stack, below a splash page) until onPageFinished is invoked...