Logical Helpers

Logical helpers provide utilities for conditional checks and logical operations in templates.

Functions

isEmpty

Checks if a value is empty.

Note: empty includes falsey values like false, 0 undefined etc.

Template Syntax

{#if isEmpty collectionToCheck}
  Collection is empty
{/if}

Parameters

Returns

boolean - true if the value is empty, false otherwise.

Example

{#if isEmpty user.posts}
  <p>You haven't made any posts yet.</p>
{else}
  <ul>
    {#each user.posts}
      <li>{this.title}</li>
    {/each}
  </ul>
{/if}

exists

Checks if a value is not empty.

Note: the same conditions as isEmpty apply, all falsey values will return false

Template Syntax

{#if exists valueToCheck}
  Value exists
{/if}

Parameters

Returns

boolean - true if the value is not empty, false otherwise.

Example

{#if exists user.name}
  <p>Welcome, {user.name}!</p>
{else}
  <p>Welcome, guest!</p>
{/if}

hasAny

Checks if an array has any elements.

Template Syntax

{#if hasAny arrayToCheck}
  Array has elements
{/if}

Parameters

Returns

boolean - true if the array has elements, false otherwise.

Example

{#if hasAny searchResults}
  <ul>
    {#each searchResults}
      <li>{this.title}</li>
    {/each}
  </ul>
{else}
  <p>No results found.</p>
{/if}

both

Checks if both a and b are truthy.

Template Syntax

{#if both conditionA conditionB}
  Both conditions are true
{/if}

Parameters

Returns

boolean - true if both values are truthy, false otherwise.

Example

{#if both isLoggedIn hasPermission}
  <button>Perform Action</button>
{else}
  <p>You don't have permission to perform this action.</p>
{/if}

either

Checks if either a or b is truthy.

Template Syntax

{#if either conditionA conditionB}
  At least one condition is true
{/if}

Parameters

Returns

boolean - true if either value is truthy, false otherwise.

Example

{#if either isAdmin isModerator}
  <button>Edit Content</button>
{else}
  <p>You don't have permission to edit this content.</p>
{/if}

maybe

Returns trueExpr if expr is truthy, falseExpr otherwise.

Template Syntax

{maybe condition 'True result' 'False result'}

Parameters

Returns

The value of trueExpr if expr is truthy, falseExpr otherwise.

Example

<p>The light is {maybe isOn 'on' 'off'}.</p>

default

Returns the fallback value if the first value is null or undefined, otherwise returns the first value.

Template Syntax

{default valueToCheck fallbackValue}

Parameters

Returns

The original value if not null/undefined, otherwise the fallback value.

Example

<p>Welcome, {default user.name 'Guest'}!</p>
<p>Items per page: {default settings.pageSize 10}</p>

Note

Uses nullish coalescing (??) internally, so only null and undefined trigger the fallback. Other falsy values like 0, false, or '' will not use the fallback.

Examples