Now I can deploy from VSTS to azure, but I can\'t run npm after deploy is successful.
Now it is work like -> run npm install for branch files => zip => copy to azure
There is no out of box build task to achieve the feature you want. If you do want to run the npm from Azure App Service:
Manually: You can go to Kudu console of the App Service and run npm command there:
Automatically: You need to create your own build task to run the npm command via Kudu Rest API