Why canvas context don't translate by global variables in ondrag event?

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Javascript

HTML5

Canvas

Consider the HTML code below:

<canvas id="taF" draggable="true" ondrag="canvasDragging(event)">
    No Canvas Support!
</canvas>

And this is `canvasDragging` and `context.translate` codes in JavaScript:

// Canvas Context

let contextX = 1000, contextY = 0;
context.translate( contextX, contextY );


// Dragging

const canvasDragging = ( event ) => {

    contextX = event.offsetX;
    contextY = event.offsetY;

}

I have checked the `event` and its properties but when I drag the canvas, the canvas isn't being translated and changed by its viewport.

Why?

What I have tried:

I think the code above is sufficient but it may not.