[英]How can I throw an error when starting an expressjs server?
這是我的最小代碼示例:
...
const url = typeof process.env.url === 'string' ? process.env.url : {do not start a server}
...
server.start(options, ({ port }) => console.log(`Server is running on http://localhost:${port}`));
如果未設置process.env.url
如何拋出錯誤(或僅打印出一些內容)並避免啟動服務器(請參見代碼示例)。
您可以簡單地拋出錯誤並退出過程:
function notValid() {
throw new Error('The passed url is not valid!');
process.exit()
}
const url = typeof process.env.url === 'string' ? process.env.url : notValid();
server.start(options, ({ port }) => console.log(`Server is running on http://localhost:${port}`));
const url = typeof process.env.url === 'string' ? process.env.url : new Error("Error Message")
if(url instanceof Error) {
throw url;
}
server.start(options, ({ port }) => console.log(`Server is running on http://localhost:${port}`));
您可以將“ Error Message
更改為所需的任何消息,這將破壞服務器(拋出錯誤)
const url = typeof process.env.url === 'string' ? process.env.url : null
if(!url) {
process.exit(0);
}
server.start(options, ({ port }) => console.log(`Server is running on http://localhost:${port}`));
一個簡單的if條件就足夠了:
const url = process.env.url || false
if(!url) {
console.log('error..');
process.exit(0)
}
...
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