noUnusedInstantiation

JavaScript (and super languages)

Summary

Rule available since: v2.3.12
Diagnostic Category: lint/correctness/noUnusedInstantiation
This rule isn’t recommended, so you need to enable it.
This rule doesn’t have a fix.
The default severity of this rule is error.
Sources:
- Same as no-new

How to configure

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{
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  "linter": {
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    "rules": {
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      "correctness": {
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        "noUnusedInstantiation": "error"
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      }
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    }
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  }
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}

Description

Disallow new operators outside of assignments or comparisons.

The goal of using new with a constructor is typically to create an object of a particular type and store that object in a variable, such as:

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const person = new Person();

It’s less common to use new and not store the result, such as:

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new Person();

In this case, the created object is thrown away because its reference isn’t stored anywhere, and in many cases, this means that the constructor should be replaced with a function that doesn’t require new to be used.

Examples

Invalid

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new Thing();

code-block.js:1:1 lint/correctness/noUnusedInstantiation ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Using the `new` operator outside of assignments or comparisons is not allowed.
  
  > 1 │ new Thing();
      │ ^^^^^^^^^^^
    2 │ 
  
  ℹ The created object is thrown away because its reference isn’t stored anywhere. Assign the object to a variable or replace with a function that doesn’t require `new` to be used.

Valid

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const thing = new Thing();