@lewiswright/vitest-plugin-vis/esm/shared/base64.js

Vitest visual testing plugin

export function isBase64String(value) {
    return typeof value === 'string' && /^([0-9a-zA-Z+/]{4})*(([0-9a-zA-Z+/]{2}==)|([0-9a-zA-Z+/]{3}=))?$/.test(value);
}