避免重复警告

【Avoiding duplicate warnings】

作为最佳实践，警告应在每个进程中只发出一次。为此，可以将 emitWarning() 放在一个布尔值判断之后。

【As a best practice, warnings should be emitted only once per process. To do so, place the emitWarning() behind a boolean.】

import { emitWarning } from 'node:process';

function emitMyWarning() {
  if (!emitMyWarning.warned) {
    emitMyWarning.warned = true;
    emitWarning('Only warn once!');
  }
}
emitMyWarning();
// Emits: (node: 56339) Warning: Only warn once!
emitMyWarning();
// Emits nothingconst { emitWarning } = require('node:process');

function emitMyWarning() {
  if (!emitMyWarning.warned) {
    emitMyWarning.warned = true;
    emitWarning('Only warn once!');
  }
}
emitMyWarning();
// Emits: (node: 56339) Warning: Only warn once!
emitMyWarning();
// Emits nothing拷贝