firebase.json

{
  "hosting": {
    "public": "builds",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ],
    "headers": [
      {
        "source": "**",
        "headers": [
          {
            "key": "Access-Control-Allow-Origin",
            "value": "*"
          },
          {
            "key": "Access-Control-Allow-Methods",
            "value": "GET, POST, PUT, DELETE, OPTIONS"
          },
          {
            "key": "Access-Control-Allow-Headers",
            "value": "Origin, X-Requested-With, Content-Type, Accept"
          },
          {
            "key": "Cross-Origin-Embedder-Policy",
            "value": "require-corp"
          },
          {
            "key": "Cross-Origin-Opener-Policy",
            "value": "same-origin"
          }
        ]
      }
    ]
  },
  "functions": [
    {
      "source": "functions",
      "codebase": "default",
      "ignore": [
        "node_modules",
        ".git",
        "firebase-debug.log",
        "firebase-debug.*.log",
        "*.local"
      ],
      "predeploy": [
        "npm --prefix \"$RESOURCE_DIR\" run build"
      ]
    }
  ]
}