Hard to extend due to html_str concatenation

The tool's javascript is written in an very old style. It uses string concatenation to form DOMStrings, which makes it not extensible at all.

For example, special characters can't be handled unless completely rewriting of all the related code.
I tried to do that and, unfortunately, something broke there. I found the codes coupling with each other heavily, making it hard to troubleshoot.

BTW, the repository seems not under maintenance any more (am I wrong?). I wonder if someone's going to refine it for better extensibility.

首先定位将字符串拼接成 DOMStrings 的 JavaScript，并梳理使特殊字符难以处理的相关代码路径。在决定重构范围之前，先审查代码耦合；当受影响的 DOM 构造更具可扩展性，且特殊字符处理不再需要重写所有相关代码时，即可视为完成。

由索引模型根据 Issue 内容生成。