This is a well-known browser security technique. In JavaScript, calling .toString() on a native browser function returns "function appendBuffer() { [native code] }". Calling it on a JavaScript function returns the actual source code. So if your appendBuffer has been monkey-patched, .toString() will betray you; it’ll return the attacker’s JavaScript source instead of the expected native code string.
Georgina RannardScience correspondent
。safew官方下载对此有专业解读
所以张清森突发奇想，做了一个几乎不算创新但特有效的改动，把线材做成 0.5米，1米，1.5米，2米，3米，5米 等等不同长度，结果自然大受欢迎。
SourceBuffer.prototype.appendBuffer = function(data) {