JavaScript Coding Conventions

In progress...

Units

• Use meters for distances.
• Use radians, not degrees, for angles.

Functions

• If a sensible default exists for a function argument or object property, don't require the user to provide it. Examples:
  • ellipsoid - Ellipsoid.getWgs84()
  • granularity - CesiumMath.toRadians(1.0)
  • height - 0.0
• Likewise if a function argument is required, throw a DeveloperError if it is not provided, not in range, etc.

Testing

• It is important to have excellent test coverage since JavaScript doesn't have the safety net of a compiler and linker.
• Prefer fine-grained tests over coarse-grained tests because they are easier to debug. In particular, only have one expect().toThrow() per spec.
• When testing for exceptions, only wrap the function call that will throw the exception. For example, prefer:

var va = Cesium.Context.createVertexArray();
va.destroy();
expect(function () { va.destroy(); }).toThrow();

over:

expect(function () { var va = Cesium.Context.createVertexArray(); va.destroy(); va.destroy(); }).toThrow();`

Otherwise, an unexpected exception can go unnoticed.