Passing variables through handlebars blockhelper - handlebars.js

Question

I want to pass and compile params in my custom block helper. I found out that the params are inside a hash-object, but how can I compile them into the partial?
I want the param flyoutClass to be compiled into my partial. Everything works fine but the place where the output of my param should be stays empty...
handlebars helper
module.exports.register = function (Handlebars, context) {
Handlebars.registerHelper('injectHtml', function(name, options) {
console.log(options.hash); //yeah my param
var partial = Handlebars.partials[name];
var template = Handlebars.compile(partial);
//var template = Handlebars.compile(partial)(options.hash); *
var output = template({"body": options.fn(this)});
return new Handlebars.SafeString(output);
//return new Handlebars.SafeString(output(options.hash)); *
//return new Handlebars.SafeString(partial(output)); *
})
};
I have already tried some things, but I always get that warning...
Warning: string is not a function
.hbs file
<div class="flyout {{flyoutClass}}">
<button>flyout-button</button>
<div class="flyout__content">
{{{body}}}
</div>
</div>
call my blockhelper
{{#injectHtml "flyout" flyoutClass='navigation__item'}}
<div class="wrapper">
<h3>Headline</h3>
<p>some copy</p>
<button>CTA</button>
</div
<div class="wrapper">
<h3>Headline</h3>
<p>some copy</p>
<button>CTA</button>
</div>
{{/injectHtml}}
UPTADE
And is it possible to pass from my blockhelper a param to another partial?
var output = template({
"addClass": options.hash.addClass,
"id": options.hash.id,
"body": options.fn(this)
});
I like to extend this partial with "id"
{{#injectHtml "flyout" flyoutClass='navigation__item'id='myUniqueID'}}
and also use it in my partial button
<div class="flyout {{flyoutClass}}">
{{>button btn="icon-text" id="{{id}}"/*[1]*/ icon="arrow-down"label="klick me"}}
<div class="flyout__content" aria-labelledby="{{id}}"/*[2]*/>
{{{body}}}
</div>
</div>
But at [1] the param isn't compiled, [2] works fine.
<div class="flyout navigation__item">
<a href="#" id="{{id}}"/*[1]*/ aria-expanded="false">
<div class="flyout__content" aria-labelledby="myUniqueID"/*[2]*/>
//html content
</div>
</div>

Answer 1

You can't "compile" the flyoutClass parameter into the partial template because you are intending this parameter to be dynamic. This means it is really just another parameter of your template data:
var output = template({
"flyoutClass": options.hash.flyoutClass,
"body": options.fn(this)
});
UPDATE
... but there is no way to add the params dynamicly??[sic]
If you wish to pass along all of the parameters passed to your helper, you could simply extend a template data object within your helper with the options.hash:
var data = Handlebars.Utils.extend({ body: options.fn(this) }, options.hash);
var output = template(data);