Pacis

Nodes

Helper Nodes

Map & MapIdx

Map Map[E any](s []E, fn func(E) Node) Node

Applies a function to each element in a slice, returning a fragment containing all resulting child nodes.

Parameters

  • s []E — Input slice of elements.
  • fn func(E) Node — Function applied to each element that produces a Node.

Returns

  • Node — A Fragment containing all nodes produced by mapping fn over s.

Usage Example

html.Map(users, func(u User) Node {
	return html.Li(html.Text(u.Name))
})

MapIdx MapIdx[E any](s []E, fn func(E, int) Node) Node

Same as Map, but also passes the index of each element to the mapping function.

Parameters

  • s []E — Input slice.
  • fn func(E, int) Node — Function that receives the element and its index.

Returns

  • Node — A Fragment containing all nodes produced by mapping fn over s with indices.

Usage Example

html.MapIdx(items, func(item string, i int) Node {
	return html.Li(html.Text(fmt.Sprintf("%d. %s", i+1, item)))
})

Iter & Iter2

Iter Iter[T any](s iter.Seq[T], fn func(T) Node) Node

Iterates over a generic sequence (iter.Seq) and applies a function to each element, returning a fragment of nodes.

Parameters

  • s iter.Seq[T] — Sequence to iterate over.
  • fn func(T) Node — Function applied to each yielded element.

Returns

  • Node — A Fragment containing all nodes produced by fn.

Usage Example

html.Iter(stream, func(value string) Node {
	return html.P(html.Text(value))
})

Iter2 Iter2[K any, V any](s iter.Seq2[K, V], fn func(K, V) Node) Node

Iterates over a key/value sequence, applying a function to each pair.

Parameters

  • s iter.Seq2[K, V] — Sequence yielding key–value pairs.
  • fn func(K, V) Node — Function applied to each key/value pair.

Returns

  • Node — A Fragment containing all nodes produced by fn.

Usage Example

html.Iter2(settings, func(k string, v any) Node {
	return html.Div(
		html.Strong(html.Text(k+":")),
		html.Span(html.Text(fmt.Sprint(v))),
	)
})

Conditional Rendering

If If(cond bool, item Item) Item

Returns item if cond is true, otherwise returns an empty fragment. Useful for conditional rendering in declarative markup.

Parameters

  • cond bool — The condition to evaluate.
  • item Item — The node to include if true.

Returns

  • Item — Either item or an empty Fragment.

Usage Example

html.If(user.LoggedIn, html.P(html.Text("Welcome back!")))

IfFn IfFn(cond bool, fn func() Item) Item

Conditionally calls and returns the result of a function if cond is true.

Parameters

  • cond bool — The condition to check.
  • fn func() Item — Function returning a node to render if true.

Returns

  • Item — Result of fn() or an empty Fragment.

Usage Example

html.IfFn(len(posts) > 0, func() Item {
	return html.Ul(html.Map(posts, func(p Post) Node {
		return html.Li(html.Text(p.Title))
	}))
})

Switch-like Rendering

SwitchCase type SwitchCase[T comparable] struct

Represents a case for a switch-like conditional structure.

Fields

  • Value []T — Values that trigger this case.
  • Fn func() Item — Function that returns the node when matched.
  • Default bool — Marks this case as the default.

Switch Switch[T comparable](expr T, cases ...*SwitchCase[T]) Item

Evaluates multiple cases against an expression, returning the node from the first match or a default case if present.

Parameters

  • expr T — The value to test.
  • cases ...*SwitchCase[T] — The cases to evaluate.

Returns

  • Item — The matching node or an empty fragment.

Usage Example

html.Switch(status,
	html.Case(html.P(html.Text("OK")), 200),
	html.Case(html.P(html.Text("Not Found")), 404),
	html.Default(html.P(html.Text("Unknown"))),
)

Case Case[T comparable](item Item, v ...T) *SwitchCase[T]

Creates a case that returns a static node when any of the values match.

Parameters

  • item Item — The node to render.
  • v ...T — Values to match.

Returns

  • *SwitchCase[T] — The constructed case.

CaseFn CaseFn[T comparable](fn func() Item, v ...T) *SwitchCase[T]

Creates a case that runs a function if the case matches.

Parameters

  • fn func() Item — Function producing the node.
  • v ...T — Values to match.

Returns

  • *SwitchCase[T] — The constructed case.

Default Default[T comparable](item Item) *SwitchCase[T]

Creates a default case that always returns the provided static node.

Parameters

  • item Item — Node to render if no cases match.

Returns

  • *SwitchCase[T] — Default case.

DefaultFn DefaultFn[T comparable](fn func() Item) *SwitchCase[T]

Creates a default case that executes the provided function when matched.

Parameters

  • fn func() Item — Function producing the node.

Returns

  • *SwitchCase[T] — Default case.

JSON Rendering

JSONNode type JSONNode struct

Represents a node that serializes arbitrary data as JSON, with optional indentation.

Fields

  • Data any — The data to encode as JSON.
  • Indent string — Indentation for formatted output.

WithIndent func (n *JSONNode) WithIndent(indent string) *JSONNode

Sets indentation for the JSON output and returns the node itself (builder-style).

Parameters

  • indent string — The indentation prefix (e.g. " ").

Returns

  • *JSONNode — The same node with updated indentation.

Render func (n *JSONNode) Render(w ChunkWriter) error

Implements rendering logic for JSON output. Serializes Data to JSON and writes it to the writer.

JSON JSON(data any) *JSONNode

Creates a new JSONNode that will serialize the given data as JSON.

Usage Example

html.Pre(html.JSON(map[string]any{
	"name": "Alice",
	"age":  28,
}).WithIndent("\t"))

Unsafe Raw HTML

type RawUnsafe string

Represents raw HTML content inserted directly into the output without escaping. triangle-alert Use cautiously — this bypasses HTML escaping and can introduce XSS vulnerabilities.

Implements

  • Item
  • Node

Render func (t RawUnsafe) Render(w ChunkWriter) error

Writes raw HTML directly to the output stream.

Usage Example

html.RawUnsafe("<b>Unescaped bold text</b>")

HTML Elements

A

A(items ...Item) *Element

Creates an HTML <a> (anchor) element for hyperlinks.

MDN Reference

Abbr

Abbr(items ...Item) *Element

Creates an HTML <abbr> element representing an abbreviation or acronym.

MDN Reference

Address

Address(items ...Item) *Element

Creates an HTML <address> element representing contact information.

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Area

Area(items ...Item) *Element

Creates an HTML <area> element for defining clickable regions in an image map.

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Article

Article(items ...Item) *Element

Creates an HTML <article> element representing self-contained content.

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Aside

Aside(items ...Item) *Element

Creates an HTML <aside> element for tangentially related content or sidebars.

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Audio

Audio(items ...Item) *Element

Creates an HTML <audio> element to embed sound content.

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B

B(items ...Item) *Element

Creates an HTML <b> element for stylistically offset text (without semantic importance).

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Base

Base(items ...Item) *Element

Creates an HTML <base> element specifying the base URL for relative URLs.

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Bdi

Bdi(items ...Item) *Element

Creates an HTML <bdi> element isolating text for bidirectional formatting.

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Bdo

Bdo(items ...Item) *Element

Creates an HTML <bdo> element to override text direction.

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Blockquote

Blockquote(items ...Item) *Element

Creates an HTML <blockquote> element for extended quotations.

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Body

Body(items ...Item) *Element

Creates an HTML <body> element representing the main document content.

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Br

Br(items ...Item) *Element

Creates an HTML <br> element for line breaks.

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Button

Button(items ...Item) *Element

Creates an HTML <button> element representing an interactive button.

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Canvas

Canvas(items ...Item) *Element

Creates an HTML <canvas> element for drawing graphics.

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Caption

Caption(items ...Item) *Element

Creates an HTML <caption> element defining a table’s title or caption.

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Cite

Cite(items ...Item) *Element

Creates an HTML <cite> element for citing a creative work.

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Code

Code(items ...Item) *Element

Creates an HTML <code> element for displaying code fragments.

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Col

Col(items ...Item) *Element

Creates an HTML <col> element defining table columns.

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Colgroup

Colgroup(items ...Item) *Element

Creates an HTML <colgroup> element grouping table columns.

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DataEl

DataEl(items ...Item) *Element

Creates an HTML <data> element linking human-readable and machine-readable content.

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Datalist

Datalist(items ...Item) *Element

Creates an HTML <datalist> element defining predefined options for inputs.

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Dd

Dd(items ...Item) *Element

Creates an HTML <dd> element defining description list details.

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Del

Del(items ...Item) *Element

Creates an HTML <del> element for deleted text.

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Details

Details(items ...Item) *Element

Creates an HTML <details> element for collapsible disclosure widgets.

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Dfn

Dfn(items ...Item) *Element

Creates an HTML <dfn> element marking a term being defined.

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Dialog

Dialog(items ...Item) *Element

Creates an HTML <dialog> element for modal or non-modal dialogs.

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Div

Div(items ...Item) *Element

Creates an HTML <div> element as a generic container.

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Dl

Dl(items ...Item) *Element

Creates an HTML <dl> element representing a description list.

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Dt

Dt(items ...Item) *Element

Creates an HTML <dt> element for a term in a description list.

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Em

Em(items ...Item) *Element

Creates an HTML <em> element for emphasizing text.

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Fieldset

Fieldset(items ...Item) *Element

Creates an HTML <fieldset> element used to group several form controls and labels.

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Figcaption

Figcaption(items ...Item) *Element

Creates an HTML <figcaption> element that provides a caption or legend for its parent <figure>.

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Figure

Figure(items ...Item) *Element

Creates an HTML <figure> element representing self-contained content, optionally with a caption.

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Form

Form(items ...Item) *Element

Creates an HTML <form> element representing a section containing interactive controls for data submission.

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H1

H1(items ...Item) *Element

Creates an HTML <h1> element for a top-level heading.

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H2

H2(items ...Item) *Element

Creates an HTML <h2> element for a second-level heading.

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H3

H3(items ...Item) *Element

Creates an HTML <h3> element for a third-level heading.

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H4

H4(items ...Item) *Element

Creates an HTML <h4> element for a fourth-level heading.

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H5

H5(items ...Item) *Element

Creates an HTML <h5> element for a fifth-level heading.

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H6

H6(items ...Item) *Element

Creates an HTML <h6> element for a sixth-level heading.

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Hgroup

Hgroup(items ...Item) *Element

Creates an HTML <hgroup> element grouping heading elements and related content.

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Hr

Hr(items ...Item) *Element

Creates an HTML <hr> element representing a thematic break between sections.

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Html

Html(items ...Item) *Element

Creates an HTML <html> element representing the root element of a document.

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I

I(items ...Item) *Element

Creates an HTML <i> element representing text set off for idiomatic or technical reasons.

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Iframe

Iframe(items ...Item) *Element

Creates an HTML <iframe> element embedding another HTML page within the current one.

MDN Reference

Img

Img(items ...Item) *Element

Creates an HTML <img> element embedding an image.

MDN Reference

Input

Input(items ...Item) *Element

Creates an HTML <input> element for data entry controls.

MDN Reference

Ins

Ins(items ...Item) *Element

Creates an HTML <ins> element representing inserted text.

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Kbd

Kbd(items ...Item) *Element

Creates an HTML <kbd> element denoting user input text.

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Label

Label(items ...Item) *Element

Creates an HTML <label> element labeling a form control.

MDN Reference

Legend

Legend(items ...Item) *Element

Creates an HTML <legend> element that provides a caption for a <fieldset>.

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Li

Li(items ...Item) *Element

Creates an HTML <li> element representing a list item.

MDN Reference

Main

Main(items ...Item) *Element

Creates an HTML <main> element representing the dominant content of the <body>.

MDN Reference

MapEl

MapEl(items ...Item) *Element

Creates an HTML <map> element used with <area> to define image maps.

MDN Reference

Mark

Mark(items ...Item) *Element

Creates an HTML <mark> element representing highlighted text for reference or emphasis.

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Meta

Meta(items ...Item) *Element

Creates an HTML <meta> element containing metadata that cannot be represented otherwise.

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Meter

Meter(items ...Item) *Element

Creates an HTML <meter> element representing a scalar or fractional measurement.

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Noscript

Noscript(items ...Item) *Element

Creates an HTML <noscript> element defining content shown when scripts are disabled.

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Object

Object(items ...Item) *Element

Creates an HTML <object> element embedding external resources such as images or plugins.

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Ol

Ol(items ...Item) *Element

Creates an HTML <ol> element representing an ordered (numbered) list.

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Optgroup

Optgroup(items ...Item) *Element

Creates an HTML <optgroup> element grouping <option> elements within a <select>.

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Option

Option(items ...Item) *Element

Creates an HTML <option> element representing an item in a selection list.

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Output

Output(items ...Item) *Element

Creates an HTML <output> element representing the result of a calculation or user action.

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P

P(items ...Item) *Element

Creates an HTML <p> element representing a paragraph of text.

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Picture

Picture(items ...Item) *Element

Creates an HTML <picture> element for responsive images using multiple sources.

MDN Reference

Pre

Pre(items ...Item) *Element

Creates an HTML <pre> element for preformatted text preserving whitespace.

MDN Reference

Progress

Progress(items ...Item) *Element

Creates an HTML <progress> element showing task completion progress.

MDN Reference

Q

Q(items ...Item) *Element

Creates an HTML <q> element representing a short inline quotation.

MDN Reference

Rp

Rp(items ...Item) *Element

Creates an HTML <rp> element defining fallback parentheses for ruby annotations.

MDN Reference

Rt

Rt(items ...Item) *Element

Creates an HTML <rt> element specifying the ruby text of a ruby annotation.

MDN Reference

Ruby

Ruby(items ...Item) *Element

Creates an HTML <ruby> element representing ruby annotations, commonly for East Asian typography.

MDN Reference

S

S(items ...Item) *Element

Creates an HTML <s> element rendering text with a strikethrough to indicate inaccuracy or irrelevance.

MDN Reference

Samp

Samp(items ...Item) *Element

Creates an HTML <samp> element representing sample output from a computer program.

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Script

Script(items ...Item) *Element

Creates an HTML <script> element embedding or referencing executable code such as JavaScript.

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Section

Section(items ...Item) *Element

Creates an HTML <section> element representing a standalone section of a document.

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Select

Select(items ...Item) *Element

Creates an HTML <select> element representing a drop-down list of options.

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Slot

Slot(items ...Item) *Element

Creates an HTML <slot> element, part of the Web Components API, acting as a placeholder for child content.

MDN Reference

Small

Small(items ...Item) *Element

Creates an HTML <small> element representing side-comments or fine print.

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Source

Source(items ...Item) *Element

Creates an HTML <source> element specifying media sources for <picture>, <audio>, or <video>.

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Span

Span(items ...Item) *Element

Creates an HTML <span> element as a generic inline container for phrasing content.

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Strong

Strong(items ...Item) *Element

Creates an HTML <strong> element indicating strong importance or urgency.

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Style

Style(items ...Item) *Element

Creates an HTML <style> element containing CSS styling declarations.

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Sub

Sub(items ...Item) *Element

Creates an HTML <sub> element displaying subscript text.

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Summary

Summary(items ...Item) *Element

Creates an HTML <summary> element defining a summary or caption for a <details> disclosure box.

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Sup

Sup(items ...Item) *Element

Creates an HTML <sup> element displaying superscript text.

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Table

Table(items ...Item) *Element

Creates an HTML <table> element representing tabular data.

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Tbody

Tbody(items ...Item) *Element

Creates an HTML <tbody> element grouping the main content rows of a table.

MDN Reference

Td

Td(items ...Item) *Element

Creates an HTML <td> element representing a data cell in a table.

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Template

Template(items ...Item) *Element

Creates an HTML <template> element holding inert DOM fragments for later use.

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Textarea

Textarea(items ...Item) *Element

Creates an HTML <textarea> element representing a multi-line text input control.

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Tfoot

Tfoot(items ...Item) *Element

Creates an HTML <tfoot> element grouping the footer rows of a table.

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Th

Th(items ...Item) *Element

Creates an HTML <th> element representing a header cell in a table.

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Thead

Thead(items ...Item) *Element

Creates an HTML <thead> element grouping header rows in a table.

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Time

Time(items ...Item) *Element

Creates an HTML <time> element representing a specific time or date.

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Title

Title(items ...Item) *Element

Creates an HTML <title> element defining the document’s title.

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Tr

Tr(items ...Item) *Element

Creates an HTML <tr> element defining a row in a table.

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U

U(items ...Item) *Element

Creates an HTML <u> element representing underlined or annotated text.

MDN Reference

Ul

Ul(items ...Item) *Element

Creates an HTML <ul> element representing an unordered (bulleted) list.

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Var

Var(items ...Item) *Element

Creates an HTML <var> element representing a variable name in a mathematical or programming context.

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Video

Video(items ...Item) *Element

Creates an HTML <video> element embedding a media player for video content.

MDN Reference

Wbr

Wbr(items ...Item) *Element

Creates an HTML <wbr> element defining a word break opportunity.

MDN Reference

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