WKWebView.EvaluateJavaScriptAsync Method
Definition
Important
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Overloads
| EvaluateJavaScriptAsync(NSString) |
Evaluates the given JavaScript string. |
| EvaluateJavaScriptAsync(String) |
Evaluates the given JavaScript string. |
EvaluateJavaScriptAsync(NSString)
Evaluates the given JavaScript string.
public virtual System.Threading.Tasks.Task<Foundation.NSObject> EvaluateJavaScriptAsync (Foundation.NSString javascript);abstract member EvaluateJavaScriptAsync : Foundation.NSString -> System.Threading.Tasks.Task<Foundation.NSObject>
override this.EvaluateJavaScriptAsync : Foundation.NSString -> System.Threading.Tasks.Task<Foundation.NSObject>Parameters
- javascript
- NSString
The JavaScript string to evaluate
Returns
A task that represents the asynchronous EvaluateJavaScript operation. The value of the TResult parameter is a WKJavascriptEvaluationResult.
Remarks
This method will throw a NSErrorException if the JavaScript is not evaluated successfully.
var config = new WKWebViewConfiguration();
var wk = new WKWebView(UIScreen.MainScreen.Bounds, config);
var js = (NSString) "document.getElementById('foo').innerHTML = 'bar'";
var result = await wk.EvaluateJavaScriptAsync(js); //== "bar"
The EvaluateJavaScriptAsync method is suitable to be used with C# async by returning control to the caller with a Task representing the operation.
The system calls completionHandler after evaluation. The arguments to the handler are an NSObject containing the results of the evaluation and an NSError if an error. If an error occurred, the result argument will be null. If no error occurred, the error argument will be null.
var config = new WKWebViewConfiguration();
var wk = new WKWebView(UIScreen.MainScreen.Bounds, config);
var js = (NSString) "document.getElementById('foo').innerHTML = 'bar'";
WKJavascriptEvaluationResult handler = (NSObject result, NSError err) => {
if(err != null)
{
System.Console.WriteLine(err);
}
if(result != null)
{
System.Console.WriteLine(result);
}
};
wk.EvaluateJavaScript(js, handler);
Applies to
EvaluateJavaScriptAsync(String)
Evaluates the given JavaScript string.
public System.Threading.Tasks.Task<Foundation.NSObject> EvaluateJavaScriptAsync (string javascript);member this.EvaluateJavaScriptAsync : string -> System.Threading.Tasks.Task<Foundation.NSObject>Parameters
- javascript
- String
A well-formed JavaScript expression.
Returns
A task that represents the asynchronous EvaluateJavaScript operation. The TResult holds the results of the evaluation.
Remarks
This method will throw a NSErrorException if the JavaScript is not evaluated successfully.
var config = new WKWebViewConfiguration();
var wk = new WKWebView(UIScreen.MainScreen.Bounds, config);
var js = (NSString) "document.getElementById('foo').innerHTML = 'bar'";
var result = await wk.EvaluateJavaScriptAsync(js); //== "bar"