@babel/plugin-proposal-class-properties

作用：用来编译类(class)

安装：npm install --save-dev @babel/plugin-proposal-class-properties

配置：.babelrc

            有参数：{ "plugins": [ ["@babel/plugin-proposal-class-properties", { "loose": true }] ] }   

             没参数：{ "plugins": ["@babel/plugin-proposal-class-properties"] }

 

有参数和没参数编译行为不同：

class Bork {

static a = 'foo';

static b;

x = 'bar';

y;

}

没参数编译结果(默认{loose:false})：

var Bork = function Bork() { babelHelpers.classCallCheck(this, Bork); Object.defineProperty(this, "x", { configurable: true, enumerable: true, writable: true, value: 'bar' }); Object.defineProperty(this, "y", { configurable: true, enumerable: true, writable: true, value: void 0 }); }; Object.defineProperty(Bork, "a", { configurable: true, enumerable: true, writable: true, value: 'foo' }); Object.defineProperty(Bork, "b", { configurable: true, enumerable: true, writable: true, value: void 0 });

 有参数编译结果：

var Bork = function Bork() { babelHelpers.classCallCheck(this, Bork); this.x = 'bar'; this.y = void 0; }; Bork.a = 'foo'; Bork.b = void 0;