lodash/internal/baseCallback.js

import baseMatches from './baseMatches';
import baseMatchesProperty from './baseMatchesProperty';
import bindCallback from './bindCallback';
import identity from '../utility/identity';
import property from '../utility/property';

/**
 * The base implementation of `_.callback` which supports specifying the
 * number of arguments to provide to `func`.
 *
 * @private
 * @param {*} [func=_.identity] The value to convert to a callback.
 * @param {*} [thisArg] The `this` binding of `func`.
 * @param {number} [argCount] The number of arguments to provide to `func`.
 * @returns {Function} Returns the callback.
 */
function baseCallback(func, thisArg, argCount) {
  var type = typeof func;
  if (type == 'function') {
    return thisArg === undefined
      ? func
      : bindCallback(func, thisArg, argCount);
  }
  if (func == null) {
    return identity;
  }
  if (type == 'object') {
    return baseMatches(func);
  }
  return thisArg === undefined
    ? property(func)
    : baseMatchesProperty(func, thisArg);
}

export default baseCallback;