我关注Get To Know Babel The JavaScript Compiler Tutorial,这是我的polygon.js
class Polygon {
constructor(height, width) {
this.height = height;
this.width = width;
}
getArea() {
return this.calcArea()
}
calcArea() {
return this.height * this.width;
}
}
我跑
babel polygon.js -o output.js
cat output.js | pbcopy
粘贴:
class Polygon {
constructor(height, width) {
this.height = height;
this.width = width;
}
getArea() {
return this.calcArea();
}
calcArea() {
return this.height * this.width;
}
}
我期待转向ES5,但代码保持不变。
发生了什么?
$ .babel --version
6.2.0 (babel-core 6.2.1)
编辑:我使用npm install babel-preset-2015 -g
~/es6:.babel polygon.js -o output.js --presets es2015
Error: Couldn't find preset "es2015" relative to directory "."
at OptionManager.mergePresets (/usr/local/lib/node_modules/babel-cli/node_modules/babel-core/lib/transformation/file/options/option-manager.js:327:17)
at OptionManager.mergeOptions (/usr/local/lib/node_modules/babel-cli/node_modules/babel-core/lib/transformation/file/options/option-manager.js:287:12)
at OptionManager.init (/usr/local/lib/node_modules/babel-cli/node_modules/babel-core/lib/transformation/file/options/option-manager.js:416:10)
at File.initOptions (/usr/local/lib/node_modules/babel-cli/node_modules/babel-core/lib/transformation/file/index.js:190:75)
at new File (/usr/local/lib/node_modules/babel-cli/node_modules/babel-core/lib/transformation/file/index.js:121:22)
at Pipeline.transform (/usr/local/lib/node_modules/babel-cli/node_modules/babel-core/lib/transformation/pipeline.js:42:16)
at transform (/usr/local/lib/node_modules/babel-cli/lib/babel/util.js:53:22)
at Object.compile (/usr/local/lib/node_modules/babel-cli/lib/babel/util.js:62:12)
at /usr/local/lib/node_modules/babel-cli/lib/babel/file.js:130:23
at arrayEach (/usr/local/lib/node_modules/babel-cli/node_modules/lodash/index.js:1289:13)
编辑:安装后问题是-g。我在本地安装并且可以正常工作。
答案 0 :(得分:4)
这也引起了我的注意。新版本的Babel要求您安装预设,可能是http://ideone.com/xR1v0j,并在CLI命令中明确指定。
根据Babel的安装位置(全局/本地),您需要安装预设位置:
npm install babel-preset-es2015
然后你可以运行Babel。例如,这会使用预设将一个文件夹中的所有文件转换为另一个文件夹。
babel [srcFolder] --out-dir [outFolder] --presets es2015