radix

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

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Some problems reported by this rule are manually fixable by editor suggestions

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. So instead of doing this:

const num = parseInt("071");      // 57
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Do this:

const num = parseInt("071", 10);  // 71
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ECMAScript 5 changed the behavior of parseInt() so that it no longer autodetects octal literals and instead treats them as decimal literals. However, the differences between hexadecimal and decimal interpretation of the first parameter causes many developers to continue using the radix parameter to ensure the string is interpreted in the intended way.

Rule Details

This rule is aimed at preventing the unintended conversion of a string to a number of a different base than intended.

Examples of incorrect code for this rule:

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/*eslint radix: "error"*/

const num = parseInt("071");

const num1 = parseInt(someValue);

const num2 = parseInt("071", "abc");

const num3 = parseInt("071", 37);

const num4 = parseInt();
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Examples of correct code for this rule:

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/*eslint radix: "error"*/

const num = parseInt("071", 10);

const num1 = parseInt("071", 8);

const num2 = parseFloat(someValue);
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Options

Deprecated: String options "always" and "as-needed" are deprecated. Setting either of these options doesn’t change the behavior of this rule, which now always enforces providing a radix, as it was the case when the "always" option was specified. Since the default radix depends on the first argument of parseInt(), this rule assumes that the second argument (the radix) is always needed.

When Not To Use It

If you want to use the default behavior of the parseInt() function when the radix argument is not specified, you can turn this rule off.

Version

This rule was introduced in ESLint v0.0.7.

Resources

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