golang template parse error while parsing index.html

[freddyisaac]

Describe the bug

The file client/build/index.html throws an error when parsed by the golang html/template package.

To Reproduce

Steps to reproduce the behavior:

1. build server using ./scripts/build.prod.sh --server
2. execute the server ./build/ratel

Expected behavior

I would have expected the error not to occur

Screenshots

The exact error is

panic: Error parsing "index.html" contents

goroutine 1 [running]:
github.com/dgraph-io/ratel/server.prepareIndexContent()
/home/freddy.isaac/projects/ratel/server/server.go:112 +0x4c8
github.com/dgraph-io/ratel/server.Run()
/home/freddy.isaac/projects/ratel/server/server.go:42 +0x25
main.main()
/home/freddy.isaac/projects/ratel/main.go:11 +0xf

It is occurring on line 17 of the file index.html which is currently

       function isTemplateAnnotation(str) {
            return (
                str.indexOf("{{") === 0 &&
                str.lastIndexOf("}}") === str.length - 2
            );
        }

However changing this code to be

       function isTemplateAnnotation(str) {
            return str.indexOf("{{") === 0 && str.lastIndexOf("}}") === str.length - 2;
        }

does however parse OK!

I believe that this may be an issue with the golang html/template package and have opened a ticket here to clarify

golang/go#73061

Environment

• OS: Ubuntu
• Go
• v1.24.1 but I have verified this back as far as v1.16

Additional context

[linear]

DGR-869 golang template parse error while parsing index.html

[freddyisaac]

Of course the golang people just closed it a functions as designed so I decided to play with it a bit
If you use

<script>
		function foo(str) {
                return str.indexOf({{"{{"}}) === 0 &&
                    str.lastIndexOf("}}") === str.length - 2;
            }
</script>

The you get this

<script>
		function foo(str) {
                return str.indexOf("{{") === 0 &&
                    str.lastIndexOf("}}") === str.length - 2;
            }
</script>

which may be what was intended ?