只读。ArrayBuffer 的长度（以字节为单位）。 ## 语法 ~~~ var arrayLength = arrayBuffer.byteLength; ~~~ ## 备注 下面的示例演示如何获取 ArrayBuffer 的字节长度。 ~~~ var req = new XMLHttpRequest(); req.open('GET', "http://www.example.com"); req.responseType = "arraybuffer"; req.send(); req.onreadystatechange = function () { if (req.readyState === 4) { var buffer = req.response; alert(buffer.byteLength); } } ~~~