Enum Preload 

pub enum Preload {
    None,
    Metadata,
    Auto,
}

The preload attribute values for media elements.

Purpose

Provides a hint to the browser about what media data to preload, balancing user experience with bandwidth and resource consumption.

Usage Context

• Used with: <audio>, <video> elements
• Performance: Controls bandwidth usage and buffering behavior
• Default: Browser-dependent (typically metadata)

Valid Values

• None: Don’t preload any data
• Metadata: Preload only metadata (duration, dimensions, first frame)
• Auto: Browser decides how much to preload (may load entire file)

Example

use ironhtml_attributes::{AttributeValue, Preload};
let preload = Preload::Metadata;
assert_eq!(preload.to_attr_value(), "metadata");

<video src="movie.mp4" preload="none" controls></video>
<video src="tutorial.mp4" preload="metadata" controls></video>
<audio src="music.mp3" preload="auto" controls></audio>

WHATWG Specification

• Media elements
• The preload attribute

Variants

None

Don’t preload any data. Minimizes bandwidth usage. User must explicitly start playback.

Metadata

Preload only metadata (duration, dimensions, track list, first frame). Good balance between UX and bandwidth.

Auto

Browser decides whether to preload data. May download the entire resource. Optimizes for user experience.

Trait Implementations

impl AttributeValue for Preload

fn to_attr_value(&self) -> Cow<'static, str>

Convert to the attribute value string.

impl Clone for Preload

fn clone(&self) -> Preload

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Preload

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Preload

fn eq(&self, other: &Preload) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Preload

impl Eq for Preload

impl StructuralPartialEq for Preload