react-form-controlled/src/utils/shallowCompare.js

Intuitive react forms for building powerful applications

const { hasOwnProperty } = Object.prototype;

/**
 * inlined Object.is polyfill to avoid requiring consumers ship their own
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/is
 */
function is(x, y) {
  // SameValue algorithm
  if (x === y) {
    // Steps 1-5, 7-10
    // Steps 6.b-6.e: +0 != -0
    return x !== 0 || 1 / x === 1 / y;
  }

  return x !== x && y !== y;
}

/**
 * Performs equality by iterating through keys on an object and returning false
 * when any key has values which are not strictly equal between the arguments.
 * Returns true when the values of all keys are strictly equal.
 */
export default function shallowEqual(objA, objB, ignore = []) {
  if (is(objA, objB)) {
    return true;
  }

  if (typeof objA !== 'object' || objA === null || typeof objB !== 'object' || objB === null) {
    return false;
  }

  const keysA = Object.keys(objA);
  const keysB = Object.keys(objB);

  if (keysA.length !== keysB.length) {
    return false;
  }

  // Test for A's keys different from B.
  for (let i = 0; i < keysA.length; i++) {
    const propName = keysA[i];
    if (ignore.indexOf(propName) !== -1) {
      continue;
    }

    if (!hasOwnProperty.call(objB, propName) || !is(objA[propName], objB[propName])) {
      return false;
    }
  }

  return true;
}