How to use client-js on Angular project

[SteveLiu1218]

I follow https://www.npmjs.com/package/skywalking-client-js/v/0.9.0

1. npm i skywalking-client-js , to my angular project.
2. import ClientMonitor from 'skywalking-client-js'; write that in my app.module.ts
   it will response
   Could not find a declaration file for module 'skywalking-client-js'. '/SkyWalkingTest/node_modules/skywalking-client-js/index.js' implicitly has an 'any' type.
   Try npm i --save-dev @types/skywalking-client-js if it exists or add a new declaration (.d.ts) file containing declare module 'skywalking-client-js';ts(7016)

what problem is here ?