The offset read-only property of the GPUCompilationMessage interface is a number representing the offset from the start of the shader code to the exact point, or the start of the relevant substring, that the message corresponds to.

A number.

To be precise, offset is the number of UTF-16 code units from the beginning of the shader code to the exact point or start of the relevant substring that the message corresponds to.

If the message does not correspond to a specific code position (perhaps it refers to the whole of the shader code), offset will be 0.

  // ...
  const shaderModule = device.createShaderModule({
    code: shaders,
  });

  const shaderInfo = await shaderModule.getCompilationInfo();
  const firstMessage = shaderInfo.messages[0];
  console.log(firstMessage.offset);
  // ...
}

See the main GPUCompilationInfo page for a more detailed example.

• The WebGPU API