Clarify preload with relation to async and defer?

[marcoscaceres]

The spec says:

The preload hint can be used by the application to initiate early fetch, but delay processing of the received response - e.g. fetch a CSS stylesheet and apply it at some later time, fetch a JavaScript asset and execute it later, and so on. Preload fetches do not block the document load event and allow the application to determine which resources are applied, when they are executed, and in which order.

Maybe clarify how this differs from async and defer in the case of scripts?

[ashumeow]

The "async" preloads during HTML parsing and will pause the HTML parser to execute it when it has finished.
The "defer" preloads during HTML parsing and will only execute it after the parser has completed.
("it" refers to data that could in the form of text, images, audio, video)

[marcoscaceres]

@ashumeow, I was hoping to see something like what you wrote in the spec itself (in non-normative prose) - in that it clarifies what this spec brings to the table :)

[ashumeow]

@marcoscaceres Thanks bro! :)

[igrigorik]

This text now lives in preload, which should address above feedback: http://w3c.github.io/preload/#early-fetch-and-application-defined-execution

[Legends]

@ashumeow This means, in case of scripts defer equals preload ?

[torian257x]

@ashumeow This means, in case of scripts defer equals preload ?

afaik yes.... just that preload doesn't have a useful fallback. Bummer.

[AliN11]

@ashumeow This means, in case of scripts defer equals preload ?

I don't think so. defer scripts are executed immediately after DOM is parsed. preload doesn't guaranty that.