Consistent use of the radix argument using parseInt

Docs > Code Analysis > Static Analysis Rules > Consistent use of the radix argument using parseInt

This page is not yet available in Spanish. We are working on its translation.
If you have any questions or feedback about our current translation project, feel free to reach out to us!

Metadata

ID: javascript-code-style/radix

Language: JavaScript

Severity: Notice

Category: Best Practices

Description

When utilizing the parseInt() function, many often skip the second parameter (the radix), allowing the function to deduce the number type based on the initial argument. By default, parseInt() can recognize both decimal and hexadecimal numbers, the latter through the 0x prefix. However, before ECMAScript 5, the function also mistakenly recognized octal numbers, leading to issues as many developers presumed a starting 0 would be disregarded.

Non-Compliant Code Examples

parseInt();
parseInt();
parseInt("10");
parseInt("10",);
parseInt((0, "10"));
parseInt((0, "10"),);
parseInt("10", null);
parseInt("10", undefined);
parseInt("10", true);
parseInt("10", "foo");
parseInt("10", "123");
parseInt("10", 1);
parseInt("10", 37);
parseInt("10", 10.5);
Number.parseInt();
Number.parseInt();
Number.parseInt("10");
Number.parseInt("10", 1);
Number.parseInt("10", 37);
Number.parseInt("10", 10.5);
parseInt?.("10");
Number.parseInt?.("10");
Number?.parseInt("10");
(Number?.parseInt)("10");

Compliant Code Examples

parseInt("10", 10);
parseInt("10", 2);
parseInt("10", 36);
parseInt("10", 0x10);
parseInt("10", 1.6e1);
parseInt("10", 10.0);
parseInt("10", foo);
Number.parseInt("10", foo);
parseInt("10", 10);
parseInt("10", 8);
parseInt("10", foo);
parseInt
Number.foo();
Number[parseInt]();
class C { #parseInt; foo() { Number.#parseInt(); } }
class C { #parseInt; foo() { Number.#parseInt(foo); } }
class C { #parseInt; foo() { Number.#parseInt(foo, 'bar'); } }
class C { #parseInt; foo() { Number.#parseInt(foo, 10); } }

// shadowed not supported
// Ignores if it's shadowed or disabled.
// var parseInt; parseInt();
// var parseInt; parseInt(foo);
// var parseInt; parseInt(foo, 10);
// var Number; Number.parseInt();
// var Number; Number.parseInt(foo);
// var Number; Number.parseInt(foo, 10);
// /* globals parseInt:off */ parseInt(foo);
// Number.parseInt(foo, 10);