noMultiAssign

JavaScript (and super languages)

Caution

This rule is part of the nursery group. This means that it is experimental and the behavior can change at any time.

Summary

• Rule available since: v2.3.11
• Diagnostic Category: lint/nursery/noMultiAssign
• This rule doesn’t have a fix.
• The default severity of this rule is information.
• Sources:
  • Inspired from no-multi-assign

How to configure

biome.json

{
  "linter": {
    "rules": {
      "nursery": {
        "noMultiAssign": "error"
      }
    }
  }
}

Description

Disallow use of chained assignment expressions

Chaining the assignment of variables can lead to unexpected results and be difficult to read.

Examples

Invalid

const foo = bar = "baz";

code-block.js:1:7 lint/nursery/noMultiAssign ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Unexpected chained assignment.
  
  > 1 │ const foo = bar = “baz”;
      │       ^^^^^^^^^^^^^^^^^
    2 │ 
  
  ℹ Variables with chained assignments in declarations may cause unintended implicit globals or unexpected scoping.
  
  ℹ Split into separate assignments.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.
  

Valid

const foo = "baz";
const bar = "baz";

Related links

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