useNumberToFixedDigitsArgument

Diagnostic Category: lint/suspicious/useNumberToFixedDigitsArgument

JavaScript (and super languages)

Since: v1.8.0

Sources:

Same as: unicorn/require-number-to-fixed-digits-argument

Description

Enforce using the digits argument with Number#toFixed().

When using Number#toFixed() explicitly specify the number of digits you want to appear after the decimal point, to avoid unexpected results, rather than relying on its default value of 0.

Examples

Invalid

const string = number.toFixed();

code-block.js:1:30 lint/suspicious/useNumberToFixedDigitsArgument  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Specify the number of digits you want to appear after the decimal point.
  
  > 1 │ const string = number.toFixed();
      │                              ^^
    2 │ 
  
  ℹ Unsafe fix: Add explicit digits argument to toFixed method.
  
    1 │ const·string·=·number.toFixed(0);
      │                               +

Valid

const string = foo.toFixed(0);

const string = foo.toFixed(2);

Caveats

This rule always assumes that toFixed is called on a number. It does not check the type of the callee.

How to configure

{
  "linter": {
    "rules": {
      "suspicious": {
        "useNumberToFixedDigitsArgument": "error"
      }
    }
  }
}