---
source: crates/biome_js_analyze/tests/spec_tests.rs
expression: invalid.js
---
# Input
```jsx
els.forEach((el) => {});

els.forEach(el => {});

els.forEach(() => {});

(els.forEach)((el) => {});

els['forEach']((el) => {});

(els['forEach'])((el) => {});

els.forEach(function(el) {}, thisArg);

```

# Diagnostics
```
invalid.js:1:1 lint/complexity/noForEach ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Prefer for...of instead of forEach.
  
  > 1 │ els.forEach((el) => {});
      │ ^^^^^^^^^^^^^^^^^^^^^^^
    2 │ 
    3 │ els.forEach(el => {});
  
  i forEach may lead to performance issues when working with large arrays. When combined with functions like filter or map, this causes multiple iterations over the same type.
  

```

```
invalid.js:3:1 lint/complexity/noForEach ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Prefer for...of instead of forEach.
  
    1 │ els.forEach((el) => {});
    2 │ 
  > 3 │ els.forEach(el => {});
      │ ^^^^^^^^^^^^^^^^^^^^^
    4 │ 
    5 │ els.forEach(() => {});
  
  i forEach may lead to performance issues when working with large arrays. When combined with functions like filter or map, this causes multiple iterations over the same type.
  

```

```
invalid.js:5:1 lint/complexity/noForEach ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Prefer for...of instead of forEach.
  
    3 │ els.forEach(el => {});
    4 │ 
  > 5 │ els.forEach(() => {});
      │ ^^^^^^^^^^^^^^^^^^^^^
    6 │ 
    7 │ (els.forEach)((el) => {});
  
  i forEach may lead to performance issues when working with large arrays. When combined with functions like filter or map, this causes multiple iterations over the same type.
  

```

```
invalid.js:7:1 lint/complexity/noForEach ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Prefer for...of instead of forEach.
  
    5 │ els.forEach(() => {});
    6 │ 
  > 7 │ (els.forEach)((el) => {});
      │ ^^^^^^^^^^^^^^^^^^^^^^^^^
    8 │ 
    9 │ els['forEach']((el) => {});
  
  i forEach may lead to performance issues when working with large arrays. When combined with functions like filter or map, this causes multiple iterations over the same type.
  

```

```
invalid.js:9:1 lint/complexity/noForEach ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Prefer for...of instead of forEach.
  
     7 │ (els.forEach)((el) => {});
     8 │ 
   > 9 │ els['forEach']((el) => {});
       │ ^^^^^^^^^^^^^^^^^^^^^^^^^^
    10 │ 
    11 │ (els['forEach'])((el) => {});
  
  i forEach may lead to performance issues when working with large arrays. When combined with functions like filter or map, this causes multiple iterations over the same type.
  

```

```
invalid.js:11:1 lint/complexity/noForEach ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Prefer for...of instead of forEach.
  
     9 │ els['forEach']((el) => {});
    10 │ 
  > 11 │ (els['forEach'])((el) => {});
       │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    12 │ 
    13 │ els.forEach(function(el) {}, thisArg);
  
  i forEach may lead to performance issues when working with large arrays. When combined with functions like filter or map, this causes multiple iterations over the same type.
  

```

```
invalid.js:13:1 lint/complexity/noForEach ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Prefer for...of instead of forEach.
  
    11 │ (els['forEach'])((el) => {});
    12 │ 
  > 13 │ els.forEach(function(el) {}, thisArg);
       │ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    14 │ 
  
  i forEach may lead to performance issues when working with large arrays. When combined with functions like filter or map, this causes multiple iterations over the same type.
  

```