Calling Helper Within If Block in Handlebars Template

Question

I am working with Handlebars.js template engine and am trying to figure out a way to do something like this (contrived example):

{{#if itemSelected "SomeItem"}}     <div>This was selected</div> {{/if} 

where itemSelected is a registered helper like this:

Handlebars.registerHelper("itemSelected", function(item) {     var selected = false;     // Lots of logic that determines if item is selected     return selected; }); 

I get errors when trying to use this syntax for the template, and I cannot find any example showing this kind of thing. I do see simple #if blocks like this...

{{#if myValueInContext}}     <div>This will show if myValueInContext results in a truthy value.</div> {{/if}} 

But, I can't figure out how to tackle the first example. Maybe I am approaching this wrong.

By the way, I tagged this Mustache as I could not add a Handlebars tag to the question.

Answer 1

With last version (1.0.rc.1) of Handlebars, you have to write sth like:

Handlebars.registerHelper('ifItemSelected', function(item, options) {   var selected = false;   // lots of logic that determines if item is selected    if (selected) {     return options.fn(this);   } }); 

ie. block(this) is replaced by options.fn(this)

http://handlebarsjs.com/block_helpers.html#conditionals

Answer 2

You should add parentheses around the embedded helper invocation:

{{#if (itemSelected "SomeItem")}}     <div>This was selected</div> {{/if} 

I did experiments and verified that it just works.

Not sure if it's mentioned in the Handlebars documentation. I learned the trick from the examples of handlebars-layouts.