RunCommandWithKudu.ps1

$env:AzureDeploymentUsername = "<deployment_credentials_username>"
$env:AzureDeploymentPassword = "deployment_credentials_password"
$env:AzureWebsiteName = "<your_site_name>"

$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $env:AzureDeploymentUsername,$env:AzureDeploymentPassword)))
$apiUrl = "https://$env:AzureWebsiteName.scm.azurewebsites.net/api/command"

$body = @{    
  command="npm install"
  dir="site"
}

$headers = @{
  "Authorization" = ("Basic {0}" -f $base64AuthInfo)
  "ContentType" = "application/json"  
}

Invoke-RestMethod -Uri $apiUrl -Headers @{Authorization=("Basic {0}" -f $base64AuthInfo)} -Method POST -ContentType "application/json" -Body (ConvertTo-Json $body) | fl