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eslint/no-loss-of-precision Correctness

✅ This rule is turned on by default.

What it does

Disallow precision loss in numeric literals.

Why is this bad?

It can lead to unexpected results in certain situations. For example, when performing mathematical operations.

In JavaScript, Numbers are stored as double-precision floating-point numbers according to the IEEE 754 standard. Because of this, numbers can only retain accuracy up to a certain amount of digits. If the programmer enters additional digits, those digits will be lost in the conversion to the Number type and will result in unexpected/incorrect behavior.

Examples

Examples of incorrect code for this rule:

var x = 2e999;

var x = 9007199254740993;

var x = 5123000000000000000000000000001;

var x = 1230000000000000000000000.0;

var x = 0x200000_0000000_1;

Examples of correct code for this rule:

var x = 12345;

var x = 123.456;

var x = 123.0;

var x = 123e34;

var x = 0x1fff_ffff_fff_fff;

How to use

To enable this rule using the config file or in the CLI, you can use:

Config (.oxlintrc.json)

{
  "rules": {
    "no-loss-of-precision": "error"
  }
}

Config (oxlint.config.ts)

import { defineConfig } from "oxlint";

export default defineConfig({
  rules: {
    "no-loss-of-precision": "error",
  },
});

CLI

oxlint --deny no-loss-of-precision

Version

This rule was added in v0.0.7.

References

• Rule Source
• Upstream rule docs
• Open rule in Oxc Playground