1. you can directly introduce
into the entrance index.html as mentioned above.
2. can also use the npm package scriptjs to directly reference a third party js, in component, such as:

import $script from 'scriptjs'

$script('xxx.js', function () {
  console.log('load xxx.js success')
})

export default class Catalogue extends Component {
...
}

can be introduced directly into index.html.

Wechat has a npm package for wx-jssdk, which is loaded into the project, import, directly and then use it according to the documentation