JS Interop interview questions

12 real JS Interop questions from the Blazor bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.

1. What is IJSRuntime?

Junior
  1. A.the injected service used to invoke browser JavaScript functions from C# code
  2. B.the wrapper passed to JavaScript so it can invoke instance methods on a specific C# object
  3. C.the method that calls a JavaScript function and asynchronously returns its result to C#
  4. D.the marker that allows JavaScript to call a specific C# method by name
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3. Which statement is correct?

Junior
  1. A.IJSRuntime — the method that calls a JavaScript function and asynchronously returns its result to C#
  2. B.IJSRuntime — the wrapper passed to JavaScript so it can invoke instance methods on a specific C# object
  3. C.IJSRuntime — the injected service used to invoke browser JavaScript functions from C# code
  4. D.IJSRuntime — the marker that allows JavaScript to call a specific C# method by name
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4. What is InvokeAsync for interop?

Mid
  1. A.the marker that allows JavaScript to call a specific C# method by name
  2. B.the wrapper passed to JavaScript so it can invoke instance methods on a specific C# object
  3. C.the injected service used to invoke browser JavaScript functions from C# code
  4. D.the method that calls a JavaScript function and asynchronously returns its result to C#
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6. Which statement is correct?

Mid
  1. A.InvokeAsync for interop — the marker that allows JavaScript to call a specific C# method by name
  2. B.InvokeAsync for interop — the wrapper passed to JavaScript so it can invoke instance methods on a specific C# object
  3. C.InvokeAsync for interop — the injected service used to invoke browser JavaScript functions from C# code
  4. D.InvokeAsync for interop — the method that calls a JavaScript function and asynchronously returns its result to C#
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7. What is JSInvokable attribute?

Mid
  1. A.the marker that allows JavaScript to call a specific C# method by name
  2. B.the injected service used to invoke browser JavaScript functions from C# code
  3. C.the method that calls a JavaScript function and asynchronously returns its result to C#
  4. D.the wrapper passed to JavaScript so it can invoke instance methods on a specific C# object
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9. Which statement is correct?

Mid
  1. A.JSInvokable attribute — the marker that allows JavaScript to call a specific C# method by name
  2. B.JSInvokable attribute — the method that calls a JavaScript function and asynchronously returns its result to C#
  3. C.JSInvokable attribute — the injected service used to invoke browser JavaScript functions from C# code
  4. D.JSInvokable attribute — the wrapper passed to JavaScript so it can invoke instance methods on a specific C# object
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10. What is DotNetObjectReference?

Senior
  1. A.the wrapper passed to JavaScript so it can invoke instance methods on a specific C# object
  2. B.the method that calls a JavaScript function and asynchronously returns its result to C#
  3. C.the injected service used to invoke browser JavaScript functions from C# code
  4. D.the marker that allows JavaScript to call a specific C# method by name
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12. Which statement is correct?

Senior
  1. A.DotNetObjectReference — the wrapper passed to JavaScript so it can invoke instance methods on a specific C# object
  2. B.DotNetObjectReference — the marker that allows JavaScript to call a specific C# method by name
  3. C.DotNetObjectReference — the method that calls a JavaScript function and asynchronously returns its result to C#
  4. D.DotNetObjectReference — the injected service used to invoke browser JavaScript functions from C# code
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