DataView.prototype.byteOffset

// ArrayBuffer 
const buffer = new ArrayBuffer(16);

const view = new DataView(buffer, 12, 4); // 12  4 

console.log(view.byteOffset);
// : 12

const buffer = new ArrayBuffer(8);
const dataview = new DataView(buffer);
dataview.byteOffset; // 0 

const dataview2 = new DataView(buffer, 3);
dataview2.byteOffset; // 3 DataView 

const buffer2 = new ArrayBuffer(16, { maxByteLength: 32 });
const dataviewLengthTracking = new DataView(buffer2, 4);
dataviewLengthTracking.byteOffset; // 4
buffer2.resize(3);
dataviewLengthTracking.byteOffset; // 0