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I'm trying to write a handlebars helper that spits out the current url query string. I will then use that query string to populate a template. I'm using assemble to do the html file generation.

My urls look like this: groups/group-details/?id=1 and I want to get at the id value.

Here is my helper:

Handlebars.registerHelper('currentId', function() {
    return document.location.search.split('?')[1].split('=')[1];
});

And I am calling it in my .hbs template like this:

{{currentId}}

I am expecting it to just spit out 1 in this example but nothing is shown.

Where am I going wrong?

- Edit -

Digging around in the web inspector console shows my helper is registered but if I put a breakpoint on the return statement, it never gets hit. I assume the helper just isn't being 'executed'.

doowb
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boz
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2 Answers2

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If you're creating the html with assemble, then assemble is doing a render pass with Handlebars. This render pass would try to resolve the {{currentId}} template on the server.

If it's doing that, I would expect an error inside the helper since document.location.search is not available. Since you aren't getting an error there, I'm assuming that the helper isn't registered with assemble and only with your front-end instance of Handlebars. If it's not registered with assemble, then {{currentId}} is interpreted as a value by Handlebars and renders nothing.

TL;DR;

When mixing front-end templates and backend templates, you need to escape the front-end templates so the backend process doesn't render them. Try using \{{currentId}} to see if the helper is used.

doowb
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  • Ok I get what you're saying. Putting in `\{{currentId}}` just outputs `{{currentId}}` in the generated html. – boz Aug 26 '16 at 08:16
  • Are you rendering templates in the browser too? If not, then I don't think `document` will be available on the server so there isn't a query string at that time. – doowb Aug 26 '16 at 13:33
  • I'm not, no. What you're saying about the query string makes perfect sense. I will have to change my approach and render templates for that set of pages in the browser. – boz Aug 26 '16 at 13:52
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Not really sure why you are going wrong.

But, I would use a regex here.

for parsing 1 out of groups/group-details/?id=1 

var a =  (new RegExp('/?id=(\d)+'));
var v = a.exec('groups/group-details/?id=1')[1];
console.log(v);

Also, I tried out

"groups/group-details/?id=1".split('?')[1].split('=')[1]

and it returns 1 fine.

The reason why i would go with regex is you are already doing two string manipulations which might not be most efficient way.

Vasif
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