useParseIntRadix

JavaScript (and super languages)

Summary

• Rule available since: v2.0.0
• Diagnostic Category: lint/correctness/useParseIntRadix
• This rule is recommended, which means is enabled by default.
• This rule has an unsafe fix.
• The default severity of this rule is information.
• Sources:
  • Same as radix

How to configure

biome.json

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

Description

Enforce the consistent use of the radix argument when using parseInt().

When using the parseInt() function it is common to omit the second argument, the radix, and let the function try to determine from the first argument what type of number it is. By default, parseInt() will autodetect decimal and hexadecimal (via 0x prefix). Prior to ECMAScript 5, parseInt() also autodetected octal literals, which caused problems because many developers assumed a leading 0 would be ignored.

This confusion led to the suggestion that you always use the radix parameter to parseInt() to eliminate unintended consequences.

Examples

Invalid

parseInt("071");
<pre class="language-text"><code class="language-text">code-block.js:1:1 <a href="https://biomejs.dev/linter/rules/use-parse-int-radix">lint/correctness/useParseIntRadix</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Missing radix parameter</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>parseInt(&quot;071&quot;);<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><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Add a non-fractional number between 2 and 36</span><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Unsafe fix</span><span style="color: lightgreen;">: </span><span style="color: lightgreen;">Add a radix of 10</span><br />  <br />  <strong>  1 │ </strong>parseInt(&quot;071&quot;<span style="color: MediumSeaGreen;">,</span><span style="opacity: 0.8;"><span style="color: MediumSeaGreen;">·</span></span><span style="color: MediumSeaGreen;">1</span><span style="color: MediumSeaGreen;">0</span>);<br />  <strong>    │ </strong>              <span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span>  <br /></code></pre>

parseInt(someValue);
<pre class="language-text"><code class="language-text">code-block.js:1:1 <a href="https://biomejs.dev/linter/rules/use-parse-int-radix">lint/correctness/useParseIntRadix</a> <span style="color: #000; background-color: #ddd;"> FIXABLE </span> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Missing radix parameter</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>parseInt(someValue);<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><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Add a non-fractional number between 2 and 36</span><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Unsafe fix</span><span style="color: lightgreen;">: </span><span style="color: lightgreen;">Add a radix of 10</span><br />  <br />  <strong>  1 │ </strong>parseInt(someValue<span style="color: MediumSeaGreen;">,</span><span style="opacity: 0.8;"><span style="color: MediumSeaGreen;">·</span></span><span style="color: MediumSeaGreen;">1</span><span style="color: MediumSeaGreen;">0</span>);<br />  <strong>    │ </strong>                  <span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span><span style="color: MediumSeaGreen;">+</span>  <br /></code></pre>

parseInt("071", "abc");
<pre class="language-text"><code class="language-text">code-block.js:1:1 <a href="https://biomejs.dev/linter/rules/use-parse-int-radix">lint/correctness/useParseIntRadix</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Invalid radix parameter</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>parseInt(&quot;071&quot;, &quot;abc&quot;);<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><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Radix must be a non-fractional number between 2 and 36</span><br />  <br /></code></pre>

parseInt("071", 37);
<pre class="language-text"><code class="language-text">code-block.js:1:1 <a href="https://biomejs.dev/linter/rules/use-parse-int-radix">lint/correctness/useParseIntRadix</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Invalid radix parameter</span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>parseInt(&quot;071&quot;, 37);<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><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Radix must be a non-fractional number between 2 and 36</span><br />  <br /></code></pre>

parseInt();
<pre class="language-text"><code class="language-text">code-block.js:1:1 <a href="https://biomejs.dev/linter/rules/use-parse-int-radix">lint/correctness/useParseIntRadix</a> ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━<br /><br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">This call to </span><span style="color: lightgreen;"><strong>parseInt</strong></span><span style="color: lightgreen;"> has no arguments, it will always return </span><span style="color: lightgreen;"><strong>NaN</strong></span><br />  <br />  <strong><span style="color: Tomato;">&gt;</span></strong> <strong>1 │ </strong>parseInt();<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><br />    <strong>2 │ </strong><br />  <br />  <strong><span style="color: lightgreen;">ℹ</span></strong> <span style="color: lightgreen;">Add arguments to this function call</span><br />  <br /></code></pre>

Valid

parseInt("071", 10);
parseInt("071", 8);
parseFloat(someValue);

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