update handlebars to 4.0

[sunng87]

No description provided.

[ehuss]

Thanks! Can you provide some more information about what has changed? Is there anything in the .hbs syntax that is different that might break existing users?

[sunng87]

@ehuss Sorry for late response. A changelog is available here. There are some minor break changes with subexpressions and template inheritance for template developer. But these should not affect current mdbook use cases.

[ehuss]

Ok, thanks!

[tuyen-at-work]

hi @ehuss @sunng87
one nice feature in handlebars 3.x is I can nest things like below:

{{#include {{#include env.txt:1}}.PublishSettings}}

Let says I have env.txt file like this:

dev-env-01

something else

Then above include would become:

{{#include dev-env-01.PublishSettings}}

I used it for my environment list and it really helpful. Few days a go I see this break and look like because we update to Handlebars 4.x