What is HTML/template in Golang?

HTML/template is a Golang (Go) package that implements data-driven templates for generating HTML outputs that are safe against code injection.

A key benefit of using HTML/template is that it produces safe, escaped HTML output using contextual auto-escaping. Therefore, whenever the output is HTML, the HTML/template package should always be used instead of text/template.

Escaping HTML output is important when preventing XSS attacks.

Syntax

HTML Syntax

HTML/template provides a rich set of control structures to render your HTML:

{{.}}: Renders the root element
{{.Title}}: Renders the “Title”-field in a nested element
{{if .Done}} {{else}} {{end}}: Defines an if-Statement
{{range .Items}} {{.}} {{end}}: Loops over all “Items” and renders each using {{.}}
{{block "myBlock" .}} {{end}}: Defines a block with the name “myBlock”
{{/* a comment */}}: Defines a comment

Functions

Common HTML/template package functions:

func New(name string) *Template: Returns a newly allocated template with given name
func (t *Template) Parse(text string) (*Template, error): Parses the given string as HTML template body for t
func ParseFiles(filenames ...string) (*Template, error): Parses HTML from file and returns a new template
func (t *Template) Execute(wr io.Writer, data interface{}) error: Applies a parsed template to the specified data object by writing wr, the output to the passed io.Writer.

package main
import (
	"html/template"
	"log"
	"os"
)
type Todo struct {
    Title string
    Done  bool
}
type PageData struct {
    PageTitle string
    Todos     []Todo
}
func main() {
    // An HTML template
	const tmpl = `
    <h1>{{.PageTitle}}</h1>
    <ul>
        {{range .Todos}}
            {{if .Done}}
                <li>{{.Title}} &#10004</li>
            {{else}}
                <li>{{.Title}}</li>
            {{end}}
        {{end}}
    </ul>`
    // Make and parse the HTML template
	t, err := template.New("webpage").Parse(tmpl)
	if err != nil {
        log.Fatal(err)
    }
    // Initialze a struct storing page data and todo data
	data := PageData {
        PageTitle: "My TODO list",
        Todos: []Todo{
            {Title: "Task 1", Done: false},
            {Title: "Task 2", Done: true},
            {Title: "Task 3", Done: true},
        },
    }
    // Render the data and output using standard output 
	t.Execute(os.Stdout, data)
}

What is HTML/template in Golang?

Syntax

HTML Syntax

Functions

Example