The new attributes introduced by html5 are: seamless, srcdoc, sandbox, manifest, charset, sizes, base, defer, defer, async, media, hreflang, ref, reversed, start, etc.
The operating environment of this tutorial: Windows 10 system, HTML5 version, Dell G3 computer.
New attributes:
Attributes added to js.
If there are no above two attributes, the execution order is loading (downloading) first A src, then execute its onload, and then execute it synchronously downwards. The defer attribute already exists before h5. Enter delayed loading (delayed execution). It will first load (download) the content of the file in src, and then wait for the page. After all loading is completed, the js.async attribute in onload is loaded asynchronously. It will execute onload immediately after loading src, and will also continue to load the page in the above execution sequence. The alert display will display b first and then a
Add the style code of the small icon to the tag in the webpage
Ordered list ol: Added start (list starting value), reversed (whether reversed) menu menu type attribute (3 menu types) embedded css style: define a style block inside the label (scoped), only valid within the style tag. Inline frame: iframe element, seamless, borderless, and borderless are added. srcdoc defines the content of the inline frame.
