prefetch/preload/prerender Diff Lookup
Distinguishes current-resource preload, future-resource prefetch and future-document prerender. Prerender uses speculation rules in this profile. Outputs describe intended work, not guaranteed browser support or network activity.
Description
Resource hints distinguish preparation for the current page from future navigation.
Resource hints distinguish preparation for the current page from future navigation. Prerendering prepares a document, whereas preload and prefetch request resources.1
Distinguishes current-resource preload, future-resource prefetch and future-document prerender. Prerender uses speculation rules in this profile. Outputs describe intended work, not guaranteed browser support or network activity.
When to use prefetch/preload/prerender Diff Lookup
Use this for the following task: Distinguishes current-resource preload, future-resource prefetch and future-document prerender. Prerender uses speculation rules in this profile. Outputs describe intended work, not guaranteed browser support or network activity.
Prepare the parsed attribute values, element states or ordered local lists requested below. Keep attribute presence separate from value.
How to use prefetch/preload/prerender Diff Lookup and understand its results
- Prepare the parsed attribute values, element states or ordered local lists requested below. Keep attribute presence separate from value.
- Enter hint using the field table, then run the tool.
- Read navigation, mechanism, preparesDocument. Interpret flags, units, ordering and placeholder values using the rules below.
- Review any reported issue or failed check, correct the supplied values when appropriate, and verify the result in its intended context.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| hint | Hint | string; choose "preload", "prefetch", "prerender" | Required |
Select the hint. Return its navigation target, mechanism and whether it prepares a document.2
preload → current/link; prefetch → future/link; prerender → future/speculation-rules This summarizes the declared operation. Units, indexing, inclusivity and exceptional cases are explained in the surrounding text.
| Output field | Meaning | Value type |
|---|---|---|
| navigation | Navigation | string |
| mechanism | Mechanism | string |
| preparesDocument | Prepares Document | boolean |
{
"input": {
"hint": "prerender"
},
"output": {
"navigation": "future",
"mechanism": "speculation-rules",
"preparesDocument": true
}
}Limitations and assumptions
The classification does not guarantee browser support or actual network work; prerender uses the speculation-rules profile here.
This evaluates supplied local information; it does not fetch a page or run a browser. Malformed requests produce input errors. A successfully evaluated request can still contain false flags, empty result lists or a result outside the supplied threshold; those outcomes have the meanings stated above.
Alternative or Complementary methods
Choose script defer/async Execution Order Table for this operation: Classifies execution scheduling of ordinary parser-inserted classic or module scripts. Async wins over defer; inline classic flags are ignored. This assumes scripting enabled and successful fetch/evaluation, without dynamic insertion or blocking attributes. For a complementary task, use Module vs Classic Script Diff Lookup for this operation: Returns standard language facts for module or classic scripts: automatic strict mode, module scope and top-level var global binding. Classic scripts can opt into strict mode separately.
Further background: HTML / accessibility reference: prefetch/preload/prerender Diff Lookup.
References
Similar or alternative tools
- script defer/async Execution Order Table
Classifies execution scheduling of ordinary parser-inserted classic or module scripts. Async wins over defer; inline classic flags are ignored. This assumes scripting enabled and successful fetch/evaluation, without dynamic insertion or blocking attributes.
- Module vs Classic Script Diff Lookup
Returns standard language facts for module or classic scripts: automatic strict mode, module scope and top-level var global binding. Classic scripts can opt into strict mode separately.