Use JavaScript to convert svg-string to base64 for css usage (Node and Browser)

Question

I have the following svg-string:

const svgString = `<svg height="210" width="400"><path d="M150 0 L75 200 L225 200 Z"/></svg>`

I would like to convert this string

const convertedSvgString = convertSvgString(svgString)

so i can use it with css mask-image

mask-image: url(`data:image/svg+xml;base64,${convertedSvgString}`)

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How do i define convertSvgString so it will work in a Node environment as well as any modern browser?