biomejs · Netail · Nov 21, 2025 · Nov 21, 2025
diff --git a/.changeset/no-ternary.md b/.changeset/no-ternary.md
@@ -0,0 +1,11 @@
+---
+"@biomejs/biome": patch
+---
+
+Added the nursery rule [`noTernary`](https://biomejs.dev/linter/rules/no-ternary/). Disallow ternary operators.
+
+**Invalid:**
+
+```js
+const foo = isBar ? baz : qux;
+```
diff --git a/crates/biome_cli/src/execute/migrate/eslint_any_rule_to_biome.rs b/crates/biome_cli/src/execute/migrate/eslint_any_rule_to_biome.rs
diff --git a/crates/biome_configuration/src/analyzer/linter/rules.rs b/crates/biome_configuration/src/analyzer/linter/rules.rs
diff --git a/crates/biome_diagnostics_categories/src/categories.rs b/crates/biome_diagnostics_categories/src/categories.rs
@@ -182,6 +182,7 @@ define_categories! {
     "lint/nursery/noReactForwardRef": "https://biomejs.dev/linter/rules/no-react-forward-ref",
     "lint/nursery/noShadow": "https://biomejs.dev/linter/rules/no-shadow",
     "lint/nursery/noSyncScripts": "https://biomejs.dev/linter/rules/no-sync-scripts",
+    "lint/nursery/noTernary": "https://biomejs.dev/linter/rules/no-ternary",
     "lint/nursery/noUnknownAttribute": "https://biomejs.dev/linter/rules/no-unknown-attribute",
     "lint/nursery/noUnnecessaryConditions": "https://biomejs.dev/linter/rules/no-unnecessary-conditions",
     "lint/nursery/noUnresolvedImports": "https://biomejs.dev/linter/rules/no-unresolved-imports",

diff --git a/crates/biome_js_analyze/src/lint/nursery.rs b/crates/biome_js_analyze/src/lint/nursery.rs
@@ -17,6 +17,7 @@ pub mod no_parameters_only_used_in_recursion;
 pub mod no_react_forward_ref;
 pub mod no_shadow;
 pub mod no_sync_scripts;
+pub mod no_ternary;
 pub mod no_unknown_attribute;
 pub mod no_unnecessary_conditions;
 pub mod no_unresolved_imports;
@@ -39,4 +40,4 @@ pub mod use_sorted_classes;
 pub mod use_spread;
 pub mod use_vue_define_macros_order;
 pub mod use_vue_multi_word_component_names;
-declare_lint_group! { pub Nursery { name : "nursery" , rules : [self :: no_continue :: NoContinue , self :: no_deprecated_imports :: NoDeprecatedImports , self :: no_empty_source :: NoEmptySource , self :: no_floating_promises :: NoFloatingPromises , self :: no_for_in :: NoForIn , self :: no_import_cycles :: NoImportCycles , self :: no_increment_decrement :: NoIncrementDecrement , self :: no_jsx_literals :: NoJsxLiterals , self :: no_misused_promises :: NoMisusedPromises , self :: no_next_async_client_component :: NoNextAsyncClientComponent , self :: no_parameters_only_used_in_recursion :: NoParametersOnlyUsedInRecursion , self :: no_react_forward_ref :: NoReactForwardRef , self :: no_shadow :: NoShadow , self :: no_sync_scripts :: NoSyncScripts , self :: no_unknown_attribute :: NoUnknownAttribute , self :: no_unnecessary_conditions :: NoUnnecessaryConditions , self :: no_unresolved_imports :: NoUnresolvedImports , self :: no_unused_expressions :: NoUnusedExpressions , self :: no_useless_catch_binding :: NoUselessCatchBinding , self :: no_useless_undefined :: NoUselessUndefined , self :: no_vue_data_object_declaration :: NoVueDataObjectDeclaration , self :: no_vue_duplicate_keys :: NoVueDuplicateKeys , self :: no_vue_reserved_keys :: NoVueReservedKeys , self :: no_vue_reserved_props :: NoVueReservedProps , self :: use_array_sort_compare :: UseArraySortCompare , self :: use_consistent_arrow_return :: UseConsistentArrowReturn , self :: use_exhaustive_switch_cases :: UseExhaustiveSwitchCases , self :: use_explicit_type :: UseExplicitType , self :: use_find :: UseFind , self :: use_max_params :: UseMaxParams , self :: use_qwik_method_usage :: UseQwikMethodUsage , self :: use_qwik_valid_lexical_scope :: UseQwikValidLexicalScope , self :: use_sorted_classes :: UseSortedClasses , self :: use_spread :: UseSpread , self :: use_vue_define_macros_order :: UseVueDefineMacrosOrder , self :: use_vue_multi_word_component_names :: UseVueMultiWordComponentNames ,] } }
+declare_lint_group! { pub Nursery { name : "nursery" , rules : [self :: no_continue :: NoContinue , self :: no_deprecated_imports :: NoDeprecatedImports , self :: no_empty_source :: NoEmptySource , self :: no_floating_promises :: NoFloatingPromises , self :: no_for_in :: NoForIn , self :: no_import_cycles :: NoImportCycles , self :: no_increment_decrement :: NoIncrementDecrement , self :: no_jsx_literals :: NoJsxLiterals , self :: no_misused_promises :: NoMisusedPromises , self :: no_next_async_client_component :: NoNextAsyncClientComponent , self :: no_parameters_only_used_in_recursion :: NoParametersOnlyUsedInRecursion , self :: no_react_forward_ref :: NoReactForwardRef , self :: no_shadow :: NoShadow , self :: no_sync_scripts :: NoSyncScripts , self :: no_ternary :: NoTernary , self :: no_unknown_attribute :: NoUnknownAttribute , self :: no_unnecessary_conditions :: NoUnnecessaryConditions , self :: no_unresolved_imports :: NoUnresolvedImports , self :: no_unused_expressions :: NoUnusedExpressions , self :: no_useless_catch_binding :: NoUselessCatchBinding , self :: no_useless_undefined :: NoUselessUndefined , self :: no_vue_data_object_declaration :: NoVueDataObjectDeclaration , self :: no_vue_duplicate_keys :: NoVueDuplicateKeys , self :: no_vue_reserved_keys :: NoVueReservedKeys , self :: no_vue_reserved_props :: NoVueReservedProps , self :: use_array_sort_compare :: UseArraySortCompare , self :: use_consistent_arrow_return :: UseConsistentArrowReturn , self :: use_exhaustive_switch_cases :: UseExhaustiveSwitchCases , self :: use_explicit_type :: UseExplicitType , self :: use_find :: UseFind , self :: use_max_params :: UseMaxParams , self :: use_qwik_method_usage :: UseQwikMethodUsage , self :: use_qwik_valid_lexical_scope :: UseQwikValidLexicalScope , self :: use_sorted_classes :: UseSortedClasses , self :: use_spread :: UseSpread , self :: use_vue_define_macros_order :: UseVueDefineMacrosOrder , self :: use_vue_multi_word_component_names :: UseVueMultiWordComponentNames ,] } }
diff --git a/crates/biome_js_analyze/src/lint/nursery/no_ternary.rs b/crates/biome_js_analyze/src/lint/nursery/no_ternary.rs
@@ -0,0 +1,69 @@
+use biome_analyze::{
+    Ast, Rule, RuleDiagnostic, RuleSource, context::RuleContext, declare_lint_rule,
+};
+use biome_console::markup;
+use biome_js_syntax::JsConditionalExpression;
+use biome_rowan::AstNode;
+use biome_rule_options::no_ternary::NoTernaryOptions;
+
+declare_lint_rule! {
+    /// Disallow ternary operators.
+    ///
+    /// The ternary operator is used to conditionally assign a value to a variable.
+    /// Some believe that the use of ternary operators leads to unclear code.
+    ///
+    /// ## Examples
+    ///
+    /// ### Invalid
+    ///
+    /// ```js,expect_diagnostic
+    /// const foo = isBar ? baz : qux;
+    /// ```
+    ///
+    /// ### Valid
+    ///
+    /// ```js
+    /// let foo;
+    ///
+    /// if (isBar) {
+    /// 	foo = baz;
+    /// } else {
+    /// 	foo = qux;
+    /// }
+    /// ```
+    ///
+    pub NoTernary {
+        version: "next",
+        name: "noTernary",
+        language: "js",
+        recommended: false,
+        sources: &[RuleSource::Eslint("no-ternary").same()],
+    }
+}
+
+impl Rule for NoTernary {
+    type Query = Ast<JsConditionalExpression>;
+    type State = ();
+    type Signals = Option<Self::State>;
+    type Options = NoTernaryOptions;
+
+    fn run(_ctx: &RuleContext<Self>) -> Self::Signals {
+        Some(())
+    }
+
+    fn diagnostic(ctx: &RuleContext<Self>, _state: &Self::State) -> Option<RuleDiagnostic> {
+        let node = ctx.query();
+        Some(
+            RuleDiagnostic::new(
+                rule_category!(),
+                node.range(),
+                markup! {
+                    "Unexpected ternary operator."
+                },
+            )
+            .note(markup! {
+                "Ternary operators can lead to unclear code. Use if-else statement instead."
+            }),
+        )
+    }
+}
diff --git a/crates/biome_js_analyze/tests/specs/nursery/noTernary/invalid.js b/crates/biome_js_analyze/tests/specs/nursery/noTernary/invalid.js
@@ -0,0 +1,7 @@
+/* should generate diagnostics */
+const foo = isBar ? baz : qux;
+
+function quux() {
+	return foo ? bar() : baz();
+}
+
diff --git a/crates/biome_js_analyze/tests/specs/nursery/noTernary/invalid.js.snap b/crates/biome_js_analyze/tests/specs/nursery/noTernary/invalid.js.snap
@@ -0,0 +1,48 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: invalid.js
+---
+# Input
+```js
+/* should generate diagnostics */
+const foo = isBar ? baz : qux;
+
+function quux() {
+	return foo ? bar() : baz();
+}
+
+
+```
+
+# Diagnostics
+```
+invalid.js:2:13 lint/nursery/noTernary ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  i Unexpected ternary operator.
+
+    1 │ /* should generate diagnostics */
+  > 2 │ const foo = isBar ? baz : qux;
+      │             ^^^^^^^^^^^^^^^^^
+    3 │ 
+    4 │ function quux() {
+
+  i Ternary operators can lead to unclear code. Use if-else statement instead.
+
+
+```
+
+```
+invalid.js:5:9 lint/nursery/noTernary ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+  i Unexpected ternary operator.
+
+    4 │ function quux() {
+  > 5 │ 	return foo ? bar() : baz();
+      │ 	       ^^^^^^^^^^^^^^^^^^^
+    6 │ }
+    7 │ 
+
+  i Ternary operators can lead to unclear code. Use if-else statement instead.
+
+
+```
diff --git a/crates/biome_js_analyze/tests/specs/nursery/noTernary/valid.js b/crates/biome_js_analyze/tests/specs/nursery/noTernary/valid.js
@@ -0,0 +1,16 @@
+/* should not generate diagnostics */
+let foo;
+
+if (isBar) {
+	foo = baz;
+} else {
+	foo = qux;
+}
+
+function quux() {
+	if (foo) {
+		return bar();
+	} else {
+		return baz();
+	}
+}
diff --git a/crates/biome_js_analyze/tests/specs/nursery/noTernary/valid.js.snap b/crates/biome_js_analyze/tests/specs/nursery/noTernary/valid.js.snap
@@ -0,0 +1,24 @@
+---
+source: crates/biome_js_analyze/tests/spec_tests.rs
+expression: valid.js
+---
+# Input
+```js
+/* should not generate diagnostics */
+let foo;
+
+if (isBar) {
+	foo = baz;
+} else {
+	foo = qux;
+}
+
+function quux() {
+	if (foo) {
+		return bar();
+	} else {
+		return baz();
+	}
+}
+
+```
diff --git a/crates/biome_rule_options/src/lib.rs b/crates/biome_rule_options/src/lib.rs
@@ -185,6 +185,7 @@ pub mod no_svg_without_title;
 pub mod no_switch_declarations;
 pub mod no_sync_scripts;
 pub mod no_template_curly_in_string;
+pub mod no_ternary;
 pub mod no_then_property;
 pub mod no_this_in_static;
 pub mod no_ts_ignore;

diff --git a/crates/biome_rule_options/src/no_ternary.rs b/crates/biome_rule_options/src/no_ternary.rs
@@ -0,0 +1,6 @@
+use biome_deserialize_macros::{Deserializable, Merge};
+use serde::{Deserialize, Serialize};
+#[derive(Default, Clone, Debug, Deserialize, Deserializable, Merge, Eq, PartialEq, Serialize)]
+#[cfg_attr(feature = "schema", derive(schemars::JsonSchema))]
+#[serde(rename_all = "camelCase", deny_unknown_fields, default)]
+pub struct NoTernaryOptions {}
diff --git a/packages/@biomejs/backend-jsonrpc/src/workspace.ts b/packages/@biomejs/backend-jsonrpc/src/workspace.ts
diff --git a/packages/@biomejs/biome/configuration_schema.json b/packages/@biomejs/biome/configuration_schema.json