---
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title: noPrecisionLoss
description: Learn more about noPrecisionLoss
---
import { Tabs, TabItem } from '@astrojs/starlight/components';

<Tabs>
<TabItem label="JavaScript (and super languages)" icon="seti:javascript">
## Summary
- Rule available since: `v1.0.0`
- Diagnostic Category: [`lint/correctness/noPrecisionLoss`](/reference/diagnostics#diagnostic-category)
- This rule is **recommended**, meaning it is enabled by default.
- This rule doesn't have a fix.
- The default severity of this rule is [**error**](/reference/diagnostics#error).
- Sources: 
  - Same as [`no-loss-of-precision`](https://eslint.org/docs/latest/rules/no-loss-of-precision)
  - Same as [`@typescript-eslint/no-loss-of-precision`](https://typescript-eslint.io/rules/no-loss-of-precision)
  - Same as [`lossy_float_literal`](https://rust-lang.github.io/rust-clippy/master/#lossy_float_literal)

## How to configure
```json title="biome.json"
{
	"linter": {
		"rules": {
			"correctness": {
				"noPrecisionLoss": "error"
			}
		}
	}
}

```
## Description
Disallow literal numbers that lose precision

## Examples

### Invalid

```js
const x = 9007199254740993
```

<pre class="language-text"><code class="language-text">code-block.js:1:11 <a href="https://biomejs.dev/linter/rules/no-precision-loss">lint/correctness/noPrecisionLoss</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">This number literal will lose precision at runtime.</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const x = 9007199254740993<br />   <strong>   │ </strong>          <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The value at runtime will be </span><span style="color: lightgreen;"><strong>9007199254740992</strong></span><br />  <br /></code></pre>

```js
const x = 5.123000000000000000000000000001
```

<pre class="language-text"><code class="language-text">code-block.js:1:11 <a href="https://biomejs.dev/linter/rules/no-precision-loss">lint/correctness/noPrecisionLoss</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">This number literal will lose precision at runtime.</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const x = 5.123000000000000000000000000001<br />   <strong>   │ </strong>          <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The value at runtime will be </span><span style="color: lightgreen;"><strong>5.123</strong></span><br />  <br /></code></pre>

```js
const x = 0x20000000000001
```

<pre class="language-text"><code class="language-text">code-block.js:1:11 <a href="https://biomejs.dev/linter/rules/no-precision-loss">lint/correctness/noPrecisionLoss</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">This number literal will lose precision at runtime.</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const x = 0x20000000000001<br />   <strong>   │ </strong>          <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The value at runtime will be </span><span style="color: lightgreen;"><strong>9007199254740992</strong></span><br />  <br /></code></pre>

```js
const x = 0x2_000000000_0001;
```

<pre class="language-text"><code class="language-text">code-block.js:1:11 <a href="https://biomejs.dev/linter/rules/no-precision-loss">lint/correctness/noPrecisionLoss</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: Tomato;">✖</span></strong> <span style="color: Tomato;">This number literal will lose precision at runtime.</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>const x = 0x2&#95;000000000&#95;0001;<br />   <strong>   │ </strong>          <strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><strong><span style="color: Tomato;">^</span></strong><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">The value at runtime will be </span><span style="color: lightgreen;"><strong>9007199254740992</strong></span><br />  <br /></code></pre>

### Valid

```js
const x = 12345
const x = 123.456
const x = 123e34
const x = 12300000000000000000000000
const x = 0x1FFFFFFFFFFFFF
const x = 9007199254740991
const x = 9007_1992547409_91
```

## Related links

- [Disable a rule](/linter/#disable-a-rule)
- [Configure the code fix](/linter#configure-the-code-fix)
- [Rule options](/linter/#rule-options)
- [Source Code](https://github.com/biomejs/biome/blob/main/crates/biome_js_analyze/src/lint/correctness/no_precision_loss.rs)
- [Test Cases](https://github.com/biomejs/biome/blob/main/crates/biome_js_analyze/tests/specs/correctness/noPrecisionLoss)

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</Tabs>