Operator '>' cannot be applied to types 'boolean' and 'number'?

https://stackoverflow.com/questions/45974764/operator-cannot-be-applied-to-types-boolean-and-number

Im using this block in my html template :

But im getting this error when i do:

ng build --prod --aot

Any suggestion how can i fix this ?

Answer:

      

Put the second expression inside parenthesis:

原因是 ， ！变成了boolean类型， 然后他 不能用>0比较。 需要吧 length>0 括号括住然后再加！。

小细节啊！