ember/template-simple-unless

April 20, 2026 · View on GitHub

💼 This rule is enabled in the 📋 template-lint-migration config.

🔧 This rule is automatically fixable by the --fix CLI option.

Require simple conditions in {{#unless}} blocks. Complex expressions should use {{#if}} with negation instead.

Rule Details

This rule enforces using simple property paths in {{#unless}} blocks rather than complex helper expressions.

Examples of incorrect code for this rule:

<template>
  {{#unless (or (eq a 1) (gt b 2))}}
    Complex condition
  {{/unless}}
</template>

<template>
  {{#unless (and isAdmin (not isBanned))}}
    Not allowed
  {{/unless}}
</template>

Examples of correct code for this rule:

<template>
  {{#unless isHidden}}
    Visible
  {{/unless}}
</template>

<template>
  {{#unless (eq value 1)}}
    Not one
  {{/unless}}
</template>

<template>
  {{#if (not (or a b))}}
    Neither
  {{/if}}
</template>

Name	Type	Default	Description
`allowlist`	`string[]`	`[]`	Helper names allowed inside `{{unless}}`.
`denylist`	`string[]`	`[]`	Helper names explicitly denied inside `{{unless}}`.
`maxHelpers`	`integer`	`1`	Maximum number of helpers allowed inside `{{unless}}` (`-1` for unlimited).