WKWebView Evaluate Javascript without reloading page

Question

Currently I can only figure out how to evaluate javascript by adding it to the webview's configuration's userContentController and reloading the page like so:

WKUserScript *script = [[WKUserScript alloc] initWithSource:source injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
[self.webView.configuration.userContentController addUserScript:script];
[self.webView reload];

How can I execute javascript on my WKWebView similarly to the old WebView's stringByEvaluatingJavaScriptFromString: so that I don't have to reload the page?

I'm trying to get something with the same effect as

[webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"document.querySelector('meta[name=viewport]').setAttribute('content', 'width=%d;', false); ", width]];

JuJoDi · Accepted Answer · 2014-07-22 01:25:02Z

12

[webView evaluateJavaScript:javascriptString completionHandler:nil];

performs the same function as the one you have listed for UIWebView

edited Jul 22, 2014 at 1:25

JuJoDi

15.1k23 gold badges87 silver badges129 bronze badges

answered Jul 22, 2014 at 1:06

rvijay007

1,35713 silver badges20 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

stk · Accepted Answer · 2014-09-21 12:24:08Z

9

You can only set the WKWebViewConfiguration at init time via the initializer

[[WKWebView alloc] initWithFrame:CGRectZero configuration:configuration];

All calls to the property configuration are copied in a later stage of runtime (see docs and Header file). So basically what you´re doing with your first three lines of code is to set the WKUserScript to a WKWebViewConfiguration which is never used - and therefore not working.

The right way to do it:

NSString *scriptString = @"Some javascript";
WKUserScript *script = [[WKUserScript alloc] initWithSource:scriptString injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
WKUserContentController *userContentController = [[WKUserContentController alloc] init];
[userContentController addUserScript:script];
WKWebViewConfiguration *configuration = [[WKWebViewConfiguration alloc] init];
configuration.userContentController = userContentController;
_webView = [[WKWebView alloc] initWithFrame:CGRectZero configuration:configuration];

After doing this, you won´t need evaluateJavaScript: anymore.

P.S.: I´m using this code in my little project STKWebKitViewController on GitHub. Maybe this will save you time, too!

edited Sep 21, 2014 at 12:24

answered Sep 7, 2014 at 17:29

stk

6,49111 gold badges46 silver badges61 bronze badges

4 Comments

abinop Over a year ago

what if you need to make consecutive calls to the web page? Would you call addUserScript every time?

stk Over a year ago

Please define "consecutive". This approach runs the same JavaScript(s) on every page load. If you want to alter which scripts are being executed, evaluateJavaScript: may be the better solution for you.

abinop Over a year ago

Say you need to call the function and pass the current timestamp as an argument on every uibutton click.How would you do it?

stk Over a year ago

Definitely evaluateJavaScript:! As you can see in the above code, with the WKUserScripts it´s only possible to execute at document start or end, not for custom events such as button clicks.

Collectives™ on Stack Overflow

WKWebView Evaluate Javascript without reloading page

2 Answers 2

Comments

4 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related