---
source: crates/biome_js_analyze/tests/spec_tests.rs
expression: noUndeclaredVariables.js
---
# Input
```jsx
// invalid
foobar;
function f() {
    lorem;
}
assignment = "value";
<Missing />;

// valid
document;
navigator;
new ArrayBuffer();
new AggregateError();

```

# Diagnostics
```
noUndeclaredVariables.js:2:1 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The foobar variable is undeclared
  
    1 │ // invalid
  > 2 │ foobar;
      │ ^^^^^^
    3 │ function f() {
    4 │     lorem;
  

```

```
noUndeclaredVariables.js:4:5 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The lorem variable is undeclared
  
    2 │ foobar;
    3 │ function f() {
  > 4 │     lorem;
      │     ^^^^^
    5 │ }
    6 │ assignment = "value";
  

```

```
noUndeclaredVariables.js:6:1 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The assignment variable is undeclared
  
    4 │     lorem;
    5 │ }
  > 6 │ assignment = "value";
      │ ^^^^^^^^^^
    7 │ <Missing />;
    8 │ 
  

```

```
noUndeclaredVariables.js:7:2 lint/correctness/noUndeclaredVariables ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! The Missing variable is undeclared
  
    5 │ }
    6 │ assignment = "value";
  > 7 │ <Missing />;
      │  ^^^^^^^
    8 │ 
    9 │ // valid
  

```