&& incorrectly is displayed as a syntax error in Lightning Component

[Alex Jung]

In lightning, you can use an expression boolean function "and" OR the corresponding logical operator:

<aura:if isTrue="{! and(this, that) }">

is functionally equivalent to:

<aura:if isTrue="{! this &amp;&amp; that }">

However, the 2nd is listed as a syntax error and breaks things like syntax completion after the ampersands.

[Alex Jung]

Interestingly,

<aura:if isTrue="{! this && that }">

is not listed as a syntax error, but fails compilation

[Scott Wells]

Thanks for filing, Alex. Should be a very minor change to the grammar for Lightning expressions. I'll try to work it in very soon.

[Scott Wells]

Alex, when I looked at the grammar it does in fact handle condition1 && condition2 and condition1 || condition2. Then I tried to reproduce the issue and am unable to do so:

Can you provide a standalone reproducible source file that demonstrates the issue you're seeing? That will help me get to the bottom of it.

Thanks!

[Alex Jung]

Good morning Scott,

I'll try to whip up a reproduction. However, I thought it'd be pretty easy to replicate :)...

One final clarification before i send a snippet: I do not think "&&" (note: w/o the character encodings) is "legal" in a *.cmp file (whereas it's ok in a VF .page). you'd need to use the encoded character entities instead.

So I believe it to NOT be working correctly if this doesn't throw a grammar error since SF won't allow this to be deployed (returning a ParseError: Message: The entity name must immediately follow the '&' in the entity reference.):

<aura:if isTrue="{! this && that}"/>

similarly this shouldn't throw a "grammar error", since SF allows this to be deployed:

<aura:if isTrue="{! this &amp;&amp; that}"/>

Also, I've found this documentation: See the "description" column for "&&" logical operator that notes that you need to escape the &'s: https://developer.salesforce.com/docs/atlas.en-us.lightning.meta/lightning/expr_operators.htm

[Scott Wells]

Ah, okay. Sounds like this is my own mistake. I typed in && but didn't save it to the server. I didn't realize that wasn't valid in Lightning expressions and I assumed that the expansion to && was a side-effect of transcribing into Markdown. I should've verified that. Let me go back to the drawing board and see if I can field this a little more accurately this time!

[Alex Jung]

<aura:component description="ic">
    <aura:attribute name="this" type="Boolean" default="false"/>
    <aura:attribute name="that" type="Boolean" default="false"/>


    <aura:if isTrue="{! and(this, that) }">
        This is valid
    </aura:if>

    <aura:if isTrue="{! this &amp;&amp; that }">
        So is this (however, note the syntax warning on the semi-colons)
    </aura:if>

    <!--<aura:if isTrue="{! this && that }">-->
        <!--Uncommenting this will prevent component from being deployed (but note, if uncommented, no syntax warnings/errors)-->
    <!--</aura:if>-->
</aura:component>

[Scott Wells]

Yup...makes total sense. This is totally my bad. I'll include the fix in a build later today. Thanks!

[Alex Jung]

Thank you! And sorry, I should have been clearer in my original issue submission to note that the char entities were "intentional" and provided that add'l info.

[Scott Wells]

Just submitted the fix. It'll be in the next build. I'm going to add a code inspection/intention to 2.0 to highlight Lightning usages of && as an error and auto-correct to && for you. Seems useful...

[Scott Wells]

Delivered in 1.8.1.1.