vue-cli3.0 使用vant

1. install 'vant' (dependencies)

    npm install vant -S

2. install 'babel-plugin-import' (devDependencies)

    npm install babel-plugin-import -D

3. config babel.config.js (hello-world/babel.config.js)

    module.exports = {
      presets: ['@vue/app'],
      
      // add begin
      plugins: [
        [
          'import',
          { libraryName: 'vant', libraryDirectory: 'es', style: true },
          'vant'
        ]
      ]
      // add end
    };

接下来就可以直接在项目中，正确的使用vant了