---
source: crates/biome_js_analyze/tests/spec_tests.rs
expression: invalid.jsonc
---
# Input
```cjs
[0, [12]].map(Number).flat();
```

# Diagnostics
```
invalid.jsonc:1:1 lint/complexity/useFlatMap  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The call chain .map().flat() can be replaced with a single .flatMap() call.
  
  > 1 │ [0, [12]].map(Number).flat();
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  
  i Safe fix: Replace the chain with .flatMap().
  
  - [0,·[12]].map(Number).flat();
  + [0,·[12]].flatMap(Number);
  

```

# Input
```cjs
[0, [12], [[16]]].map(Number).flat(1);
```

# Diagnostics
```
invalid.jsonc:1:1 lint/complexity/useFlatMap  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The call chain .map().flat() can be replaced with a single .flatMap() call.
  
  > 1 │ [0, [12], [[16]]].map(Number).flat(1);
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  
  i Safe fix: Replace the chain with .flatMap().
  
  - [0,·[12],·[[16]]].map(Number).flat(1);
  + [0,·[12],·[[16]]].flatMap(Number);
  

```

# Input
```cjs
[0, [12], [[16]]].map((element) => {}).flat(1);
```

# Diagnostics
```
invalid.jsonc:1:1 lint/complexity/useFlatMap  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The call chain .map().flat() can be replaced with a single .flatMap() call.
  
  > 1 │ [0, [12], [[16]]].map((element) => {}).flat(1);
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  
  i Safe fix: Replace the chain with .flatMap().
  
  - [0,·[12],·[[16]]].map((element)·=>·{}).flat(1);
  + [0,·[12],·[[16]]].flatMap((element)·=>·{});
  

```

# Input
```cjs
[0, [12], [[16]]].map((element, index) => {}).flat(1);
```

# Diagnostics
```
invalid.jsonc:1:1 lint/complexity/useFlatMap  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The call chain .map().flat() can be replaced with a single .flatMap() call.
  
  > 1 │ [0, [12], [[16]]].map((element, index) => {}).flat(1);
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  
  i Safe fix: Replace the chain with .flatMap().
  
  - [0,·[12],·[[16]]].map((element,·index)·=>·{}).flat(1);
  + [0,·[12],·[[16]]].flatMap((element,·index)·=>·{});
  

```

# Input
```cjs
[0, [12], [[16]]].map((element, index, array) => {}).flat(1);
```

# Diagnostics
```
invalid.jsonc:1:1 lint/complexity/useFlatMap  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The call chain .map().flat() can be replaced with a single .flatMap() call.
  
  > 1 │ [0, [12], [[16]]].map((element, index, array) => {}).flat(1);
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  
  i Safe fix: Replace the chain with .flatMap().
  
  - [0,·[12],·[[16]]].map((element,·index,·array)·=>·{}).flat(1);
  + [0,·[12],·[[16]]].flatMap((element,·index,·array)·=>·{});
  

```