no-loss-of-precision

Configuration

Preset	Configured Value
✅ js.configs.recommended	`"error"`
✅ ts.configs.recommended	`"error"`

rslint.config.ts

import { defineConfig, js } from '@rslint/core';

export default defineConfig([
  js.configs.recommended,
  {
    rules: {
      'no-loss-of-precision': 'error',
    },
  },
]);

Disallow literal numbers that lose precision.

Rule Details

This rule prevents the use of number literals that lose precision when converted to a JavaScript Number due to 64-bit floating-point rounding.

JavaScript Numbers are represented as 64-bit floating-point values according to the IEEE 754 standard. This means they can only accurately represent integers up to Number.MAX_SAFE_INTEGER (2^53 - 1 = 9007199254740991). Numbers exceeding this limit, or decimal numbers with too many significant digits, will lose precision at runtime.

Examples of incorrect code for this rule:

// Integers exceeding MAX_SAFE_INTEGER
var x = 9007199254740993;

// Very large integers with precision loss
var x = 5123000000000000000000000000001;

// Decimals with too many significant digits
var x = 1.0000000000000000000000123;

// Scientific notation causing precision loss
var x = 9.007199254740993e15;

// Binary, octal, hex exceeding safe limits
var x = 0x20000000000001;
var x = 0o400000000000000001;
var x = 0b100000000000000000000000000000000000000000000000000001;

// Numbers that become Infinity
var x = 2e999;

Examples of correct code for this rule:

// Safe integers
var x = 12345;
var x = 9007199254740991; // MAX_SAFE_INTEGER

// Safe decimals
var x = 123.456;
var x = 0.00000000000000000000000123;

// Safe scientific notation
var x = 123e34;

// Safe binary, octal, hex
var x = 0x1fffffffffffff;
var x = 0o377777777777777777;
var x = 0b11111111111111111111111111111111111111111111111111111;

// Using numeric separators (ES2021)
var x = 9007_1992547409_91;

Options

This rule has no options.

When Not To Use It

If you don't mind the precision loss in certain numeric literals, you can disable this rule.

Original Documentation

ESLint no-loss-of-precision

#no-loss-of-precision

#Configuration

#Rule Details

#Options