useObjectSpread (JavaScript)

Language JavaScript (and super languages)

Summary

Rule available since: v2.0.0
Diagnostic Category: lint/style/useObjectSpread
This rule isn’t recommended, so you need to enable it.
This rule has a safe fix.
The default severity of this rule is information.
Sources:
- Same as prefer-object-spread
- Inspired from e18e/prefer-spread-syntax

How to configure

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{
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  "linter": {
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    "rules": {
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      "style": {
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        "useObjectSpread": "error"
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      }
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    }
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  }
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}

Description

Prefer object spread over Object.assign() when constructing new objects.

Object spread syntax is more concise, more readable, and performs better than Object.assign() when creating a new object from existing objects. It also has better TypeScript integration.

Examples

Invalid

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Object.assign({}, foo);

code-block.js:1:1 lint/style/useObjectSpread  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Object spread syntax is more concise, readable, and performs better than Object.assign.
  
  > 1 │ Object.assign({}, foo);
      │ ^^^^^^^^^^^^^
    2 │ 
  
  ℹ Safe fix: Replace Object.assign({...}, <object>) with { ...<object> }.
  
    1   │ - Object.assign({},·foo);
      1 │ + ({...foo,});
    2 2 │

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Object.assign({}, { foo: 'bar' });

code-block.js:1:1 lint/style/useObjectSpread  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Object spread syntax is more concise, readable, and performs better than Object.assign.
  
  > 1 │ Object.assign({}, { foo: 'bar' });
      │ ^^^^^^^^^^^^^
    2 │ 
  
  ℹ Safe fix: Replace Object.assign({...}, <object>) with { ...<object> }.
  
    1   │ - Object.assign({},·{·foo:·'bar'·});
      1 │ + ({foo:·'bar'·,});
    2 2 │

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Object.assign({ foo: 'bar' }, baz);

code-block.js:1:1 lint/style/useObjectSpread  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Object spread syntax is more concise, readable, and performs better than Object.assign.
  
  > 1 │ Object.assign({ foo: 'bar' }, baz);
      │ ^^^^^^^^^^^^^
    2 │ 
  
  ℹ Safe fix: Replace Object.assign({...}, <object>) with { ...<object> }.
  
    1   │ - Object.assign({·foo:·'bar'·},·baz);
      1 │ + ({foo:·'bar'·,...baz,});
    2 2 │

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Object.assign({}, baz, { foo: 'bar' });

code-block.js:1:1 lint/style/useObjectSpread  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Object spread syntax is more concise, readable, and performs better than Object.assign.
  
  > 1 │ Object.assign({}, baz, { foo: 'bar' });
      │ ^^^^^^^^^^^^^
    2 │ 
  
  ℹ Safe fix: Replace Object.assign({...}, <object>) with { ...<object> }.
  
    1   │ - Object.assign({},·baz,·{·foo:·'bar'·});
      1 │ + ({...baz,foo:·'bar'·,});
    2 2 │

Valid

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({ ...foo });

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({ ...baz, foo: 'bar' });

Modifying an existing object is allowed:

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Object.assign(foo, { bar: baz });