Nice idea. Will have a think but am initially keen on it.

agreed, would be nice!

@seven-phases-max What do you think?

Assuming it's relatively lightweight, why not?

@lejenome We'll take your other commit too, please, so this also applies to less tags

done

thanks then!
Would you like to make a pull request with some documentation to less-docs?

I would but my English really sucks
just some notes:

• importance level: window.less < script tag < link tag
• data attributes names are not camelCase (e.g logLevel -> data-log-level)
• link tag options are just render time options (e.g verbose, logLevel, ... are not supported)
• non-string data attributes values should be JSON valid (e.g use double quotes instead of single quotes like in data-global-vars='{ myvar: "#ddffee", mystr: "\"quoted\"" }')

No problem, myself or someone else will get round to it.

docs added: less/less-docs@ebf87fc
will go live when next version released.

This conflicts with RequireJS's data-main attribute on line JSON.parse(tag.dataset[opt]) because tag.dataset[opt] is not JSON, it is a link to another JS file:

<script data-main="js/main.js" src="bower/requirejs/require.js" type="text/javascript"></script>

Instead of going through all options at least check for only known ones:

var stringOptions = ['env', 'dumpLineNumbers', 'rootpath', 'errorReporting',
    jsonOptions = ['...'];

// ...

if (stringOptions.indexOf(opt) != -1) {
    options[opt] = tag.dataset[opt];
} else if (jsonOptions.indexOf(opt) != -1) {
    options[opt] = JSON.parse(tag.dataset[opt]);
} else {
    // do nothing
}