prefer-numeric-literals

Disallow parseInt() and Number.parseInt() in favor of binary, octal, and hexadecimal literals

The parseInt() and Number.parseInt() functions can be used to turn binary, octal, and hexadecimal strings into integers. As binary, octal, and hexadecimal literals are supported in ES6, this rule encourages use of those numeric literals instead of parseInt() or Number.parseInt().

0b111110111 === 503;
0o767 === 503;
1
2

Rule Details

This rule disallows calls to parseInt() or Number.parseInt() if called with two arguments: a string; and a radix option of 2 (binary), 8 (octal), or 16 (hexadecimal).

Examples of incorrect code for this rule:

/*eslint prefer-numeric-literals: "error"*/

parseInt("111110111", 2) === 503;
parseInt(`111110111`, 2) === 503;
parseInt("767", 8) === 503;
parseInt("1F7", 16) === 503;
Number.parseInt("111110111", 2) === 503;
Number.parseInt("767", 8) === 503;
Number.parseInt("1F7", 16) === 503;
1
2
3
4
5
6
7
8
9

Examples of correct code for this rule:

/*eslint prefer-numeric-literals: "error"*/

parseInt(1);
parseInt(1, 3);
Number.parseInt(1);
Number.parseInt(1, 3);

0b111110111 === 503;
0o767 === 503;
0x1F7 === 503;

a[parseInt](1,2);

parseInt(foo);
parseInt(foo, 2);
Number.parseInt(foo);
Number.parseInt(foo, 2);
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17

When Not To Use It

If you want to allow use of parseInt() or Number.parseInt() for binary, octal, or hexadecimal integers, or if you are not using ES6 (because binary and octal literals are not supported in ES5 and below), you may wish to disable this rule.

Compatibility

• JSCS: requireNumericLiterals

Version

This rule was introduced in ESLint v3.5.0.

Resources

• Rule source
• Tests source