DataView.prototype.byteLength

 byteLength 属性描述了视图从它的 ArrayBuffer 开始的字节长度。

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dataview.byteLength

byteLength 属性是一个获取(accessor)属性，它的 set 属性为 undefined，这意味着它是只读的。值在 DataView 被创建时就确定了，且不能改变。如果 DataView 没有指定偏移量或byteLength，那么被引用的 ArrayBuffer 的字节长度将被返回。

var buffer = new ArrayBuffer(8);
var dataview = new DataView(buffer);
dataview.byteLength; // 8 (matches the byteLength of the buffer)

var dataview2 = new DataView(buffer, 1, 5);
dataview2.byteLength; // 5 (as specified when constructing the DataView)

var dataview3 = new DataView(buffer, 2);
dataview3.byteLength; // 6 (due to the offset of the constructed DataView)

• DataView
• ArrayBuffer