eslint-plugin-use-numeric-separator

use-numeric-separator is an ESLint plugin to enforce usage of the numeric separator (that '_' that can go in the middle of numbers) for large numbers.

// Hard to read:
10000000
// Easy to read:
10_000_000

This plugin has support for decimal, hexadecimal, octal, and binary literals, and has separate configurable options for each base to specify the threshold at which to start applying the rule, and the number of digits per group.

With default options:

// Incorrect:
10000000
0xDEADBEEF
0b10101010

// Correct:
10_000_000
0xDE_AD_BE_EF
0b1010_1010

// Also correct:
1000 // short number
100.0000001 // decimals are not split
6.02214e+23 // scientific notation is ignored

Options

Each base has its own rule with threshold and groupSize options, with defaults. threshold is the number of digits above which the rule should apply, and groupSize is the number of digits between each separator. Here is an example .eslintrc.json with every rule on and set to the default values:

{
  ...
  "rules": {
    "use-numeric-separator/decimal": [
      "error",
      {
        "threshold": 5,
        "groupSize": 3
      }
    ],
    "use-numeric-separator/hexadecimal": [
      "error",
      {
        "threshold": 7,
        "groupSize": 2
      }
    ],
    "use-numeric-separator/binary": [
      "error",
      {
        "threshold": 5,
        "groupSize": 4
      }
    ],
    "use-numeric-separator/octal": [
      "error",
      {
        "threshold": 5,
        "groupSize": 3
      }
    ]
  }
}