process.exitCode
当进程正常退出或通过 process.exit()
退出而不指定代码时,将作为进程退出码的数字。
将代码指定为 process.exit(code)
将覆盖 process.exitCode
的任何先前设置。
A number which will be the process exit code, when the process either
exits gracefully, or is exited via process.exit()
without specifying
a code.
Specifying a code to process.exit(code)
will override any
previous setting of process.exitCode
.