Function getDeprecationWarningEmitter

lib/internal/util.js:113–136

(
  code, msg, deprecated, useEmitSync,
  shouldEmitWarning = () => true,
)

let validateOneOf;

function getDeprecationWarningEmitter(
  code, msg, deprecated, useEmitSync,
  shouldEmitWarning = () => true,
) {
  let warned = false;
  return function(arg) {
    if (!warned && shouldEmitWarning(arg)) {
      warned = true;
      if (code === 'ExperimentalWarning') {
        process.emitWarning(msg, code, deprecated);
      } else if (code !== undefined) {
        if (!codesWarned.has(code)) {
          const emitWarning = useEmitSync ?
            require('internal/process/warning').emitWarningSync :
            process.emitWarning;
          emitWarning(msg, 'DeprecationWarning', code, deprecated);
          codesWarned.add(code);
        }
      } else {
        process.emitWarning(msg, 'DeprecationWarning', deprecated);
      }
    }
  };
}

function isPendingDeprecation() {
  return getOptionValue('--pending-deprecation') &&