noAssignInExpressions

Ce contenu n’est pas encore disponible dans votre langue.

JavaScript (and super languages)

Summary

Rule available since: v1.0.0
Diagnostic Category: lint/suspicious/noAssignInExpressions
This rule is recommended, which means is enabled by default.
This rule doesn’t have a fix.
The default severity of this rule is error.
Sources:
- Inspired from no-cond-assign

Description

Disallow assignments in expressions.

In expressions, it is common to mistype a comparison operator (such as ==) as an assignment operator (such as =). Moreover, the use of assignments in expressions is confusing. Indeed, expressions are often considered as side-effect free.

Examples

Invalid

1
let a, b;
2
a = (b = 1) + 1;

code-block.ts:2:6 lint/suspicious/noAssignInExpressions ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ The assignment should not be in an expression.
  
    1 │ let a, b;
  > 2 │ a = (b = 1) + 1;
      │      ^^^^^
    3 │ 
  
  ℹ The use of assignments in expressions is confusing.
    Expressions are often considered as side-effect free.

1
let a;
2
if (a = 1) {
3
}

code-block.ts:2:5 lint/suspicious/noAssignInExpressions ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ The assignment should not be in an expression.
  
    1 │ let a;
  > 2 │ if (a = 1) {
      │     ^^^^^
    3 │ }
    4 │ 
  
  ℹ The use of assignments in expressions is confusing.
    Expressions are often considered as side-effect free.

1
function f(a) {
2
    return a = 1;
3
}

code-block.ts:2:12 lint/suspicious/noAssignInExpressions ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ The assignment should not be in an expression.
  
    1 │ function f(a) {
  > 2 │     return a = 1;
      │            ^^^^^
    3 │ }
    4 │ 
  
  ℹ The use of assignments in expressions is confusing.
    Expressions are often considered as side-effect free.

Valid

1
let a;
2
a = 1;

How to configure

1
{
2
  "linter": {
3
    "rules": {
4
      "suspicious": {
5
        "noAssignInExpressions": "error"
6
      }
7
    }
8
  }
9
}