Develop Reference

VueJs Conditional handlebars

I'm trying to use VueJs conditional rendering using handlebars in vueJs 2.0 as per their documentation but eslint is coming back with and error:
- avoid using JavaScript keyword as property name: "if" in expression {{#if ok}}
- avoid using JavaScript keyword as property name: "if" in expression {{/if}}
VueJs does not seem to be rendering it.
<!-- Handlebars template -->
{{#if ok}}
<h1>Yes</h1>
{{/if}}

If you are trying to use Vue.js syntax, the documentation outlines just a few lines down what's done for Vue.js. You would use the v-if directive.
<h1 v-if="ok">Yes</h1>
If like you mentioned, you're wanting to use Handlebars alongside Vue.js, note that both of them use the same {{ curly braces in templates. You may need to change Vue's use of the curly braces like so...
Vue.config.delimiters = ['<%', '%>'];

Either:
Using v-if to conditionally render
<h1 v-if="isVisible"> Yes </h1>
or using v-show to add a hidden attribute to that element style
<h1 v-show="isVisible"> Yes </h1>
either can be used but be careful with v-if since the element won't be in the DOM if the condition is not met.

I believe that is simply to document that the conditional does not go on a parent tag, but rather it is placed directly on the node that you want to conditionally display.
In other words its simply a comparison not part of Vue.js markup, but rather part of Handlebars.

Vue conditional rendering syntax
<h1 v-if="ok">Yes</h1>
<h1 v-show="ok">Yes</h1>
Details in original docs.
https://v2.vuejs.org/v2/guide/conditional.html#v-if-vs-v-show

Firstly, You should look at the vue documentation .https://v2.vuejs.org/v2/guide/conditional.html#v-if-vs-v-showjs and by the way, you can use "v-if" and "v-show"attributes, in flowing related to
examples.
<h1 v-if='isShow'>Test</h1>
<h1 v-show='isShow'>Test</h1>

For anyone coming here from a search trying to conditionally render inside {{ }} braces, you could always use a computed property:
import { computed } from 'vue';
<script setup>
const submitButtonText = computed(() => {
return props.formObject ? 'Save' : 'Create';
});
</script>
<template>
<form>
<button type="submit">
{{ submitButtonText }}
</button>
</form>
</template>
v-if and v-if-else work perfect for large elements, but this is great for simple one-line conditional text.

Angular - check if class is odd or even on ng-click

I have the following ng-repeat that gives an element a className based on whether it is even or odd...
<div ng-click="displayHTML(content)" ng-class-odd="'title'" ng-class-even="'html'" ng-repeat="content in name.name">
{{content}}
</div>
On ng-click I am calling displayHTML() and passing a parameter content so that only that particular div that is clicked calls the function.
However on ng-click I'm attempting to see whether the clicked element is ng-class-odd or ng-class-even and I want the function to only be called if the element is ng-class-odd.
But I do not know an easy way to do this. Is there an easy "angular" way of doing it. If not, what should I put here...
$scope.displayHTML = function(obj){
////
}

ngRepeat exposes several local variables to the scope, specifically $even and $odd. Just use those:
<div ng-click="displayHTML(content, $even)" ng-class-odd="'title'" ng-class-even="'html'" ng-repeat="content in name.name">
{{content}}
</div>
js:
$scope.displayHTML = function(obj, $even) {
if($even) {/* even code*/}
else {/* odd code */}
}

Compare angular index variable in smarty tags

I want to catch the first iteration in ng-repeat directive:
<div ng-repeat="product in products">
<div is-open="{if "[[$index]]" == 0}true{else}false{/if}">
...
</div>
</div>
But it doesn't work. Setting 0 as string also doesn't work. Comparing in angular also doesn't work.
How can I do that?

Try:
<div is-open="{{$index == 0}}"></div>

You should use special property $first of ng-repeat with ternary operator. Like see below snippet
<div ng-repeat="product in products">
<div is-open="($first) ? true : false">
...
</div>
</div>
I suppose smarty code will not work as you're expecting. Smarty is a server side programming language and angular runs on client side. In your query, smarty tags are unnecessary being called in angular directive. Above trick will work for you.
There are also some couple of special properties available too. You can check them out here

$scope variables shortcuts in AngularJs Templates

In my controller I assign:
$scope.currentThing.data
And in my template sometimes I need
currentThing.data.response[0].hello
and sometimes
currentThing.data.otherStuff[0].goodbye
//or
currentThing.data.anotherThing[0].goodMorning
So I was wondering if it is possible to create a shortcut for this variables straight in the templates, something like:
{{response = currentThing.data.response[0]}}
So that I can use it like this {{response.hello}}.
In general, is it possible to assign temporary variables from the template? I don't need to have any data-binding, I would need them only for generating the template and then they can disappear forever

You can do that in controller like here: http://jsbin.com/moyuhe/1/edit
app.controller('firstCtrl', function($scope){
$scope.currentThing = {
data: [
{response:[
{hello:1},
{hello:2}
]}
]
};
$scope.temp = $scope.currentThing.data[0];
});
HTML:
<div ng-controller="firstCtrl">
{{temp.response |json }}
</div>

You might be able to use ngInit: https://docs.angularjs.org/api/ng/directive/ngInit
Although it seems that using it outside of ngRepeat is frowned upon.
<div ng-init="myvar = currentThing.data.response[0]">
<span>{{myvar.hello}}</span>
</div>
I haven't tested it like this but that's the closest thing I can think of that may solve your problem.

Yes, it is possible using syntax like
{{ variable = ( expression ) }}
anywhere in HTML template (not just ng-init as some suggest).
It is exceptionally useful in cases when you need to use a calculated variable more times - it does not need to be calculated each time.
Some example
<!-- can use it before -->
<p> Calculated value is {{calculated}} </p>
<div ng-repeat=" item in calculated = ( allItems | filter1 | filter2 | filter3 ) ">
{{item}}
</div>
<!-- can use it after-->
<p> Calculated value is still {{calculated}} </p>
Edit: so in your case
{{response = ( currentThing.data.response[0] ) }}

I want Handlebar {{#if}} logic inside of a Ember.Handlebars.helper

I am converting someone else's code to Handlebars.js and I'm stuck on converting this tag to its {{#handle-bar}}{{/handle-bar}} counterpart.
The previous coder used an {{#ifCond}} to toggle what 'selected'. This is my component.
{{#dropdown-item }}
{{unbound this.itemName}}
{{/dropdown-item}}
Here is the div i want converted to my component
<div class="dropdownItem" {{bind-attr value=formField_DropdownItemID}}{{#ifCond formField_DropdownItemID value}} selected{{/ifCond}} >
{{unbound this.itemName}}
</div>
My first thought was to just pop the div's logic into the the component, like the next example, but this gave me an error.
{{#dropdown-item bind-attr value=formField_DropdownItemID {{#ifCond formField_DropdownItemID value}} selected{{/ifCond}} }}
{{unbound this.itemName}}
{{/dropdown-item}}
Any suggestions?

You can set those properties to compute. The syntax would be:
{{#dropdown-item selected=computedProperty value=formField_DropdownItemID}}
computedProperty can deal with your conditional logic. The whole idea is to pull that out of handlebars anyways. :)