Develop a comprehensive currency converter using HTML5, CSS3, JavaScript and a reliable Exchange Rate API. Create a clean, intuitive interface with prominent input fields and currency selectors. Implement real-time exchange rates with timestamp indicators showing data freshness. Support 170+ global currencies including crypto with appropriate symbols and formatting. Maintain a conversion history log with timestamps and rate information. Allow users to bookmark favorite currency pairs for quick access. Generate interactive historical rate charts with customizable date ranges. Implement offline functionality using cached exchange rates with clear staleness indicators. Add a built-in calculator for complex conversions and arithmetic operations. Create rate alerts for target exchange rates with optional notifications. Include side-by-side comparison of different provider rates when available. Support printing and exporting conversion results in multiple formats (PDF, CSV, JSON).
使用 HTML5、CSS3、JavaScript 以及一个可靠的汇率 API，开发一个综合性的货币换算工具。打造简洁直观的界面，设置醒目的输入框和货币选择器。实现实时汇率功能，并附带时间戳指示器以展示数据的时效性。支持 170 多种全球货币，包括加密货币，并配备相应的符号和格式化规则。维护一份带有时间戳和汇率信息的换算历史记录。允许用户收藏常用的货币对，以便快速访问。生成可自定义日期范围的交互式历史汇率图表。使用缓存的汇率实现离线功能，并附带清晰的数据陈旧度提示。内置计算器，以支持复杂的换算和算术运算。提供目标汇率提醒功能，并可选择开启通知。在可用时，纳入不同数据源汇率的并排对比。支持以多种格式（PDF、CSV、JSON）打印和导出换算结果。