SendGrid Handlebars变量taskCount在greaterThan块内多次调用失效问题

• SendGrid 封装的 greaterThan 等自定义条件块助手存在作用域覆盖行为：当你进入 {{#greaterThan 条件}} 包裹的代码块时，块内的默认上下文会被替换为条件判断的布尔返回值（也就是此处的 true），不再默认继承父级的全局数据上下文。
• 第一层 greaterThan 判断时还处于全局上下文，所以可以正常读取到 taskCount=5 进入对应分支，但进入块内部后，直接调用 taskCount 相当于在布尔值 true 上查找同名属性，自然找不到返回空值，因此触发了 insert 标签的默认值1，嵌套的 greaterThan taskCount 1 也因为拿不到值判断不成立，没有输出 (s)。

把块内所有调用 taskCount 的地方改为回退到父级上下文，或者直接引用根上下文即可，两种写法都可以生效：

1. 用 ../ 回退父级上下文

{{#greaterThan taskCount 0}} 
Congrats on starting {{insert ../taskCount "default=1"}} task{{#greaterThan ../taskCount 1}} (s){{/greaterThan}} and taking the first small step. 
{{else}}
You have not started a task yet. What are you waiting for? It has been {{DaysSinceJoined}} days since you joined on {{JoinedAt}}. 

You have missed {{DaysSinceJoined}} days where you could been making Small Steps towards the dreams of you better tomorrow. 
{{/greaterThan}}

2. 用 @root 直接引用根上下文

{{#greaterThan taskCount 0}} 
Congrats on starting {{insert @root.taskCount "default=1"}} task{{#greaterThan @root.taskCount 1}} (s){{/greaterThan}} and taking the first small step. 
{{else}}
You have not started a task yet. What are you waiting for? It has been {{DaysSinceJoined}} days since you joined on {{JoinedAt}}. 

You have missed {{DaysSinceJoined}} days where you could been making Small Steps towards the dreams of you better tomorrow. 
{{/greaterThan}}

内容的提问来源于stack exchange，提问作者ChampChris