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@babel/plugin-transform-numeric-separator

信息

此插件包含在 @babel/preset-env 中，位于 ES2021

示例​

十进制字面量​

JavaScript
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

二进制字面量​

JavaScript
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

十六进制字面量​

JavaScript
// 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

八进制字面量​

挥手表情符号

八进制非常适合表示权限，但在 0o0000 形式下看起来更好。这里使用分隔符没有实际好处。

安装​

npm install --save-dev @babel/plugin-transform-numeric-separator

用法​

babel.config.json
{
  "plugins": ["@babel/plugin-transform-numeric-separator"]
}

通过 CLI​

Shell
babel --plugins @babel/plugin-transform-numeric-separator script.js

通过 Node API​

JavaScript
require("@babel/core").transformSync("code", {
  plugins: ["@babel/plugin-transform-numeric-separator"],
});

附加信息​

如果需要将 ES2015 十进制、二进制、十六进制和八进制数字表示形式进一步编译为其 ES2015 之前的数字字面量形式，请添加 "@babel/plugin-transform-literals" 插件

信息

@babel/plugin-transform-literals 已包含在 @babel/preset-env 中。

babel.config.json
{
  "presets": ["@babel/preset-env"],
  "plugins": ["@babel/plugin-transform-numeric-separator"]
}
{
  "plugins": ["@babel/plugin-transform-numeric-separator", "@babel/plugin-transform-literals"]
}

参考​