Read Javascript variable from .NET in Blazor Webassembly

Question

I am new to Blazor Webassembly and find out how to call a javascript function from .NET code. My question is: Is it possible to read and write also a javascript variable from .NET. Here an example:

Javascript code loaded into page:

var Namespace1 = {
    prop1: 42, 
    func1: function () {
        return 42;
    }
}

from .NET I can call the function Namespace1.func1:

@code { 
    //private int prop1 { get; set; } = 1;
    private int ret1 { get; set; }

    override protected async Task OnInitializedAsync() {
        // Error: The value 'window.Namespace1.prop1' is not a function.
        // ret1 = await JSRuntime.InvokeAsync<int>("Namespace1.prop1"); 
        ret1 = await JSRuntime.InvokeAsync<int>("Namespace1.func1");
        // return base.OnInitializedAsync();
    }
}

Is it possible to access also Namespace1.prop1 from .NET

Umair · Accepted Answer · 2020-09-09 18:40:49Z

5

That's not possible currently as IJsRuntime only exposes methods that invoke javascript functions. Details here on Microsoft docs

But you can write a js function and return a property:

var Namespace1 = {
    prop1: 42, 
    func1: function () {
        return prop1;
    }
}

answered Sep 9, 2020 at 18:40

Umair

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2 Comments

H.G. Sandhagen Over a year ago

Thank you for the information. Because it is for a project with a js lib (not my code) with a lot of properties it will not work. I will use angular for this.

Umair Over a year ago

You can create your own javascript that can have functions that can access the js properties that you want to access. So basically blazor > your js > readonly js

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