How to Repeat HTML Lines Multiple Times Using Golang Templates?

Iterating HTML in Golang Templates

In Golang, when iterating over a list of elements in a template, you can use the {{range}} action. However, it requires an array or slice to iterate through. To repeat an HTML line multiple times, we can create an empty slice and populate it with either a zero value or specific values.

Using Zero-Value Slice

We can create an empty slice make([]struct{}, n) to represent the number of iterations we need. Then, in the template, we use the {{range}}${} syntax to iterate over the slice. For example:

tmpl := template.Must(template.New("").Parse(`
<ul>
{{range $idx, $e := .}}
    <li><a href="/?p={{idx}}">{{$idx}}</a></li>
{{end}}
</ul>`))
n := 5
tmpl.Execute(w, make([]struct{}, n))

Using Filled Slice

Alternatively, we can fill the slice with specific values. This approach allows us to skip using the index ($idx) in the HTML code. For example:

tmpl := template.Must(template.New("").Parse(`
<ul>
{{range .}}
    <li><a href="/?p={{.}}">{{.}}</a></li>
{{end}}
</ul>`))
values := make([]int, 5)
for i := range values {
    values[i] = i + 1
}
tmpl.Execute(w, values)

Using Zero-Value Slice and Custom Function

Another option is to create a custom function that adds 1 to the slice index and returns the result. This allows you to use the slice indices while incrementing the numbers by 1. For example:

tmpl := template.Must(template.New("").Funcs(template.FuncMap{
    "Add": func(i int) int { return i + 1 },
}).Parse(`
<ul>
{{range $idx, $e := .}}{{$idx := (Add $idx)}}
    <li><a href="/?p={{$idx}}">{{$idx}}</a></li>
{{end}}
</ul>`))
n := 5
tmpl.Execute(w, make([]struct{}, n))

These approaches provide flexible ways to repeat an HTML line multiple times based on your specific requirements.

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