noUselessDateGetTime (JavaScript)

Language JavaScript (and super languages)

Summary

Rule available since: v2.6.0
Diagnostic Category: lint/nursery/noUselessDateGetTime
This rule has an unsafe fix.
The default severity of this rule is warning.
Sources:
- Same as unicorn/consistent-date-clone

How to configure

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

Description

Disallow calling .getTime() on a date before passing it to the Date constructor.

Passing a Date object to new Date() creates a copy of it. Calling .getTime() on the date first does the same thing with extra code.

Examples

Invalid

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const copy = new Date(date.getTime());

code-block.js:1:28 lint/nursery/noUselessDateGetTime  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ This .getTime() call is unnecessary.
  
  > 1 │ const copy = new Date(date.getTime());
      │                            ^^^^^^^^^
    2 │ 
  
  ℹ Passing a date directly to new Date() already creates a copy of it.
  
  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.
  
  ℹ Unsafe fix: Remove the .getTime() call.
  
    1   │ - const·copy·=·new·Date(date.getTime());
      1 │ + const·copy·=·new·Date(date);
    2 2 │

Valid

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const copy = new Date(date);
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const timestamp = date.getTime();