@babel/plugin-proposal-numeric-separator
NOTE: This plugin is included in
@babel/preset-env
Example
Decimal Literals
let budget = 1_000_000_000_000;
// What is the value of `budget`? It's 1 trillion!
//
// Let's confirm:
console.log(budget === 10 ** 12); // true
Binary Literals
let nibbles = 0b1010_0001_1000_0101;
// Is bit 7 on? It sure is!
// 0b1010_0001_1000_0101
// ^
//
// We can double check:
console.log(!!(nibbles & (1 << 7))); // true
Hex Literal
// Messages are sent as 24 bit values, but should be
// treated as 3 distinct bytes:
let message = 0xa0_b0_c0;
// What's the value of the upper most byte? It's A0, or 160.
// We can confirm that:
let a = (message >> 16) & 0xff;
console.log(a.toString(16), a); // a0, 160
// What's the value of the middle byte? It's B0, or 176.
// Let's just make sure...
let b = (message >> 8) & 0xff;
console.log(b.toString(16), b); // b0, 176
// What's the value of the lower most byte? It's C0, or 192.
// Again, let's prove that:
let c = message & 0xff;
console.log(c.toString(16), b); // c0, 192
Octal Literal
hand wave emoji
Octals are great for permissions, but also look better when represented in 0o0000 form. No real benefit with separators here.
Installation
npm install --save-dev @babel/plugin-proposal-numeric-separator
Usage
With a configuration file (Recommended)
{
"plugins": ["@babel/plugin-proposal-numeric-separator"]
}
Via CLI
babel --plugins @babel/plugin-proposal-numeric-separator script.js
Via Node API
require("@babel/core").transformSync("code", {
plugins: ["@babel/plugin-proposal-numeric-separator"],
});
Additional Information
If you need to further compile ES2015 Decimal, Binary, Hex and Octal number representations to their pre-ES2015 numeric literal form, add the "@babel/plugin-transform-literals" plugin:
@babel/plugin-transform-literalsis already included in @babel/preset-env and @babel/preset-es2015.
With a configuration file (Recommended)
{
"presets": ["@babel/preset-env"],
"plugins": ["@babel/plugin-proposal-numeric-separator"]
}
{
"plugins": ["@babel/plugin-proposal-numeric-separator", "@babel/plugin-transform-literals"]
}