Go Templates: Hyphens

In Go templates, you may have noticed the use of hyphens (-) in constructs like {{- end -}}. These hyphens serve specific purposes in template rendering, enabling you to control the whitespace and formatting of your output.

Here's how hyphens are used in Go templates:

Leading Hyphens ({{- ...}})

Placing hyphens immediately after the opening curly brace ({{) trims any whitespace and newline characters that follow. This ensures that the content right after the opening brace is rendered immediately, without any leading whitespace.

Example:

Hello, 
{{- " this will have no leading whitespace." }}

Output:

Hello, this will have no leading whitespace.

In this example, the use of leading hyphens ensures that the text immediately follows the opening curly brace without any leading whitespace.

Trailing Hyphens ({{ ... -}})

When hyphens are placed just before the closing curly brace (}}), any trailing whitespace and newline characters are trimmed. This prevents extra whitespace from being added after the content enclosed by the template tags.

Example:

{{ "This will have no trailing whitespace. " -}}
Goodbye!

Output:

This will have no trailing whitespace. Goodbye!

Here, the trailing hyphens ensure that there's no trailing whitespace after the content enclosed by the template tags.

Both Leading and Trailing Hyphens ({{- ... -}})

Using hyphens on both sides trims both leading and trailing whitespace, resulting in tight control over the spacing and formatting of your content.

Example:

Hello, 
{{- " this will have no trailing whitespace. " -}}
Goodbye!

Output:

Hello, this will have no trailing whitespace. Goodbye!

With both leading and trailing hyphens, the content is rendered without any unnecessary whitespace.