Function determineSpecificType

lib/internal/errors.js:1008–1056

* Determine the specific type of a value for type-mismatch errors. * @param {*} value * @returns {string}

(value)

 * @returns {string}
 */
function determineSpecificType(value) {
  if (value === null) {
    return 'null';
  } else if (value === undefined) {
    return 'undefined';
  }

  const type = typeof value;

  switch (type) {
    case 'bigint':
      return `type bigint (${value}n)`;
    case 'number':
      if (value === 0) {
        return 1 / value === -Infinity ? 'type number (-0)' : 'type number (0)';
      } else if (value !== value) { // eslint-disable-line no-self-compare
        return 'type number (NaN)';
      } else if (value === Infinity) {
        return 'type number (Infinity)';
      } else if (value === -Infinity) {
        return 'type number (-Infinity)';
      }
      return `type number (${value})`;
    case 'boolean':
      return value ? 'type boolean (true)' : 'type boolean (false)';
    case 'symbol':
      return `type symbol (${String(value)})`;
    case 'function':
      return `function ${value.name}`;
    case 'object':
      if (value.constructor && 'name' in value.constructor) {
        return `an instance of ${value.constructor.name}`;
      }
      return `${lazyInternalUtilInspect().inspect(value, { depth: -1 })}`;
    case 'string':
      value.length > 28 && (value = `${StringPrototypeSlice(value, 0, 25)}...`);
      if (StringPrototypeIndexOf(value, "'") === -1) {
        return `type string ('${value}')`;
      }
      return `type string (${JSONStringify(value)})`;
    default:
      value = lazyInternalUtilInspect().inspect(value, { colors: false });
      if (value.length > 28) {
        value = `${StringPrototypeSlice(value, 0, 25)}...`;
      }

      return `type ${type} (${value})`;
  }
}

/**
 * Create a list string in the form like 'A and B' or 'A, B, ..., and Z'.