Simple Salesforce DX project configuration file to activate Salesforce Extensions for Visual Studio Code.

sfdx-project.json

{
    "packageDirectories": [
        {
            "path": "force-app",
            "default": true
        }
    ],
    "namespace": "",
    "sfdcLoginUrl": "https://login.salesforce.com",
    "sourceApiVersion": "45.0"
}

Remember to increment the sourceApiVersion with each Salesforce major release.

When working with a source-tracked org, such as a scratch org, then packageDirectories should list your source folders for pushing and pulling metadata. Commonly, this folder is named force-app.

When working with a non-source-tracked org, such as a sandbox or production org, then an entry in packageDirectories should refer to the relative path to your folder of metadata in the Metadata API format. Commonly, this folder is named src instead of force-app.