---
source: crates/biome_js_analyze/tests/spec_tests.rs
expression: invalidFunctions.js
---
# Input
```jsx
export function f(x) {
    if(x) {
        // assign 'y'
        var /* @type number */ y /*: number */ = 2*x;
        // assign 'y' to 'x'
        x = y;
    }
    return x;
}
```

# Diagnostics
```
invalidFunctions.js:4:9 lint/style/noVar  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ! Use let or const instead of var.
  
    2 │     if(x) {
    3 │         // assign 'y'
  > 4 │         var /* @type number */ y /*: number */ = 2*x;
      │         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    5 │         // assign 'y' to 'x'
    6 │         x = y;
  
  i A variable declared with var is accessible in the whole body of the function. Thus, the variable can be accessed before its initialization and outside the block where it is declared.
  
  i See MDN web docs for more details.
  
  i Unsafe fix: Use 'const' instead.
  
    2 2 │       if(x) {
    3 3 │           // assign 'y'
    4   │ - ········var·/*·@type·number·*/·y·/*:·number·*/·=·2*x;
      4 │ + ········const·/*·@type·number·*/·y·/*:·number·*/·=·2*x;
    5 5 │           // assign 'y' to 'x'
    6 6 │           x = y;
  

```