Javascript – Running JavaScript in a UIWebView before any other JavaScript is run

code-injectioniphonejavascriptuiwebview

I have a UIWebView component that is going to load a webpage which might contain JavaScript. I want to run some JavaScript of my own before any JavaScript on the loaded webpage runs. I know I can use [myWebView stringByEvaulatingJavaScriptFromString:] on the webViewDidFinishLoad: delegate of the UIWebView, however this will only run my JavaScript after the JavaScript on the webpage is run.

Is the only solution to inject my JavaScript into the source code of the webpage? For example, I would put it immediately after the <head> tag to insure it is the first JavaScript that is run.

Best Solution

I would like an answer to this question as well. I can get it to work for the initial loading of the page by putting [myWebView stringByEvaluatingJavaScriptFromString: js] inside webViewDidStartLoad. On refresh, however, it does not appear to work.

Edit: I found this work-around (similar to the suggestion in your question.) Not sure how robust it is. http://www.stevesaxon.me/posts/2011/window-external-notify-in-ios-uiwebview/

Related Solutions

Javascript – Selecting and manipulating CSS pseudo-elements such as ::before and ::after using javascript (or jQuery)

You could also pass the content to the pseudo element with a data attribute and then use jQuery to manipulate that:

In HTML:

<span>foo</span>

In jQuery:

$('span').hover(function(){
    $(this).attr('data-content','bar');
});

In CSS:

span:after {
    content: attr(data-content) ' any other text you may want';
}

If you want to prevent the 'other text' from showing up, you could combine this with seucolega's solution like this:

In HTML:

<span>foo</span>

In jQuery:

$('span').hover(function(){
    $(this).addClass('change').attr('data-content','bar');
});

In CSS:

span.change:after {
    content: attr(data-content) ' any other text you may want';
}

Ios – UIWebView loading but not displaying website (XCode 4, iOS SDK 4.3)

If you hooked everything up in Interface Builder correctly, the following lines should not be needed:

if(!webView)
{
    webView = [[UIWebView alloc]init];
}

webView.delegate = self;

Try removing them and see what happens. Also, put an NSLog(...) in the webView:didFailLoadWithError: callback and see if it is output.

Best Solution

Related Solutions

Javascript – Selecting and manipulating CSS pseudo-elements such as ::before and ::after using javascript (or jQuery)

Ios – UIWebView loading but not displaying website (XCode 4, iOS SDK 4.3)

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