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eggjs
Common egg Error Codes
前置资料
- 参考 Node.js Error Codes: https://npm.taobao.org/mirrors/node/latest/docs/api/errors.html#errors_node_js_error_codes
- 所有由 egg 和 egg 插件引起已知的 Error 异常，都需要规范 err.code
RFC：How to create an Error
Usage
- built-in Error
const errors = require('egg').errors;
const err = new errors.TypeError('ERR_EGG_SOME_ERROR_CODE_STRING', 'Some error haha');
console.log(err.code); // 'ERR_EGG_SOME_ERROR_CODE_STRING'
- custom Error
const errors = require('egg').errors;
// register a new subclass of TypeError with code 'ERR_EGG_MY_ERROR'
// if code 'ERR_EGG_MY_ERROR' exists, then will throw a TypeError with code 'ERR_EGG_DUPLICATE_CODE'
errors.E('ERR_EGG_MY_ERROR', TypeError);
const err = new errors.ERR_EGG_MY_ERROR('my error here');
console.log(err.name); // 'TypeError'
console.log(err.code); // 'ERR_EGG_MY_ERROR'
message and code
An error should contains two message and code properties by default.
message maybe change cause by typo, but it won't cause major change, it juest patch or minor change.
code should keep stable after it first come out.
https://github.com/nodejs/node/blob/master/lib/internal/errors.js#L100
example: https://github.com/nodejs/node/blob/4d89e3c261ebd67baf4ac3d17033419e1b3075f2/lib/internal/url.js#L827
if (typeof method !== 'function') {
throw new errors.TypeError('ERR_ARG_NOT_ITERABLE', 'Query pairs');
}
用途：
- 规范化错误名
- 报错提示可以 i18n
- 便于开发者 google 检索报错
- 可以提供类似 angular 这样的指引: https://docs.angularjs.org/error/$compile/baddir，即 error 输出简单的提示，并输出一条链接，开发者点击后可以访问官网看详细的指引。
https://github.com/nodejs/node/blob/master/doc/guides/using-internal-errors.md
没有暴露出来，得 egg 自行实现了
https://github.com/eggjs/egg/issues/1047#issue-235462770 补充来 RFC 说明，egg 默认提供一个 errors 帮助类，快速自定义自己的异常。
