src/Util/Util.js
function deepEq(a, b, aStack, bStack) {
  // Compare `[[Class]]` names.
  var className = Object.prototype.toString.call(a);
  if (className !== Object.prototype.toString.call(b)) {
    return false;
  }

  /* eslint-disable no-fallthrough */
  switch (className) {
    // Strings, numbers, regular expressions, dates, and booleans are compared by value.
    case "[object RegExp]":
    // RegExps are coerced to strings for comparison (Note: '' + /a/i === '/a/i')
    case "[object String]":
      // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
      // equivalent to `new String("5")`.
      return "" + a === "" + b;
    case "[object Number]":
      // `NaN`s are equivalent, but non-reflexive.
      // Object(NaN) is equivalent to NaN
      if (+a !== +a) {
        return +b !== +b;
      }

      // An `egal` comparison is performed for other numeric values.
      return +a === 0 ? 1 / +a === 1 / b : +a === +b;
    case "[object Date]":
    case "[object Boolean]":
      // Coerce dates and booleans to numeric primitive values. Dates are compared by their
      // millisecond representations. Note that invalid dates with millisecond representations
      // of `NaN` are not equivalent.
      return +a === +b;
    /* eslint-enable no-fallthrough */
  }

  var areArrays = className === "[object Array]";
  if (!areArrays) {
    if (typeof a != "object" || typeof b != "object") {
      return false;
    }

    // Objects with different constructors are not equivalent, but `Object`s or `Array`s
    // from different frames are.
    var aCtor = a.constructor,
      bCtor = b.constructor;
    if (
      aCtor !== bCtor &&
      !(
        isFunction(aCtor) &&
        aCtor instanceof aCtor &&
        isFunction(bCtor) &&
        bCtor instanceof bCtor
      ) &&
      ("constructor" in a && "constructor" in b)
    ) {
      return false;
    }
  }
  // Assume equality for cyclic structures. The algorithm for detecting cyclic
  // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.

  // Initializing stack of traversed objects.
  // It's done here since we only need them for objects and arrays comparison.
  aStack = aStack || [];
  bStack = bStack || [];
  var length = aStack.length;
  while (length--) {
    // Linear search. Performance is inversely proportional to the number of
    // unique nested structures.
    if (aStack[length] === a) {
      return bStack[length] === b;
    }
  }

  // Add the first object to the stack of traversed objects.
  aStack.push(a);
  bStack.push(b);

  // Recursively compare objects and arrays.
  if (areArrays) {
    // Compare array lengths to determine if a deep comparison is necessary.
    length = a.length;
    if (length !== b.length) {
      return false;
    }
    // Deep compare the contents, ignoring non-numeric properties.
    while (length--) {
      if (!eq(a[length], b[length], aStack, bStack)) {
        return false;
      }
    }
  } else {
    // Deep compare objects.
    var keys = Object.keys(a),
      key;
    length = keys.length;
    // Ensure that both objects contain the same number of properties before comparing deep equality.
    if (Object.keys(b).length !== length) {
      return false;
    }
    while (length--) {
      // Deep compare each member
      key = keys[length];
      if (!(has(b, key) && eq(a[key], b[key], aStack, bStack))) {
        return false;
      }
    }
  }
  // Remove the first object from the stack of traversed objects.
  aStack.pop();
  bStack.pop();

  return true;
}
function deepEq(a, b, aStack, bStack) {
  // Compare `[[Class]]` names.
  var className = Object.prototype.toString.call(a);
  if (className !== Object.prototype.toString.call(b)) {
    return false;
  }

  /* eslint-disable no-fallthrough */
  switch (className) {
    // Strings, numbers, regular expressions, dates, and booleans are compared by value.
    case "[object RegExp]":
    // RegExps are coerced to strings for comparison (Note: '' + /a/i === '/a/i')
    case "[object String]":
      // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
      // equivalent to `new String("5")`.
      return "" + a === "" + b;
    case "[object Number]":
      // `NaN`s are equivalent, but non-reflexive.
      // Object(NaN) is equivalent to NaN
      if (+a !== +a) {
        return +b !== +b;
      }

      // An `egal` comparison is performed for other numeric values.
      return +a === 0 ? 1 / +a === 1 / b : +a === +b;
    case "[object Date]":
    case "[object Boolean]":
      // Coerce dates and booleans to numeric primitive values. Dates are compared by their
      // millisecond representations. Note that invalid dates with millisecond representations
      // of `NaN` are not equivalent.
      return +a === +b;
    /* eslint-enable no-fallthrough */
  }

  var areArrays = className === "[object Array]";
  if (!areArrays) {
    if (typeof a != "object" || typeof b != "object") {
      return false;
    }

    // Objects with different constructors are not equivalent, but `Object`s or `Array`s
    // from different frames are.
    var aCtor = a.constructor,
      bCtor = b.constructor;
    if (
      aCtor !== bCtor &&
      !(
        isFunction(aCtor) &&
        aCtor instanceof aCtor &&
        isFunction(bCtor) &&
        bCtor instanceof bCtor
      ) &&
      ("constructor" in a && "constructor" in b)
    ) {
      return false;
    }
  }
  // Assume equality for cyclic structures. The algorithm for detecting cyclic
  // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.

  // Initializing stack of traversed objects.
  // It's done here since we only need them for objects and arrays comparison.
  aStack = aStack || [];
  bStack = bStack || [];
  var length = aStack.length;
  while (length--) {
    // Linear search. Performance is inversely proportional to the number of
    // unique nested structures.
    if (aStack[length] === a) {
      return bStack[length] === b;
    }
  }

  // Add the first object to the stack of traversed objects.
  aStack.push(a);
  bStack.push(b);

  // Recursively compare objects and arrays.
  if (areArrays) {
    // Compare array lengths to determine if a deep comparison is necessary.
    length = a.length;
    if (length !== b.length) {
      return false;
    }
    // Deep compare the contents, ignoring non-numeric properties.
    while (length--) {
      if (!eq(a[length], b[length], aStack, bStack)) {
        return false;
      }
    }
  } else {
    // Deep compare objects.
    var keys = Object.keys(a),
      key;
    length = keys.length;
    // Ensure that both objects contain the same number of properties before comparing deep equality.
    if (Object.keys(b).length !== length) {
      return false;
    }
    while (length--) {
      // Deep compare each member
      key = keys[length];
      if (!(has(b, key) && eq(a[key], b[key], aStack, bStack))) {
        return false;
      }
    }
  }
  // Remove the first object from the stack of traversed objects.
  aStack.pop();
  bStack.pop();

  return true;
}
function deepEq ( a , b , aStack , bStack ) { // Compare `[[Class]]` names. var className = Object . prototype . toString . call ( a ) ; if ( className !== Object . prototype . toString . call ( b ) ) { return false ; } /* eslint-disable no-fallthrough */ switch ( className ) { // Strings, numbers, regular expressions, dates, and booleans are compared by value. case "[object RegExp]" : // RegExps are coerced to strings for comparison (Note: '' + /a/i === '/a/i') case "[object String]" : // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is // equivalent to `new String("5")`. return "" + a === "" + b ; case "[object Number]" : // `NaN`s are equivalent, but non-reflexive. // Object(NaN) is equivalent to NaN if ( + a !== + a ) { return + b !== + b ; } // An `egal` comparison is performed for other numeric values. return + a === 0 ? 1 / + a === 1 / b : + a === + b ; case "[object Date]" : case "[object Boolean]" : // Coerce dates and booleans to numeric primitive values. Dates are compared by their // millisecond representations. Note that invalid dates with millisecond representations // of `NaN` are not equivalent. return + a === + b ; /* eslint-enable no-fallthrough */ } var areArrays = className === "[object Array]" ; if ( ! areArrays ) { if ( typeof a != "object" || typeof b != "object" ) { return false ; } // Objects with different constructors are not equivalent, but `Object`s or `Array`s // from different frames are. var aCtor = a . constructor , bCtor = b . constructor ; if ( aCtor !== bCtor && ! ( isFunction ( aCtor ) && aCtor instanceof aCtor && isFunction ( bCtor ) && bCtor instanceof bCtor ) && ( "constructor" in a && "constructor" in b ) ) { return false ; } } // Assume equality for cyclic structures. The algorithm for detecting cyclic // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`. // Initializing stack of traversed objects. // It's done here since we only need them for objects and arrays comparison. aStack = aStack || [ ] ; bStack = bStack || [ ] ; var length = aStack . length ; while ( length -- ) { // Linear search. Performance is inversely proportional to the number of // unique nested structures. if ( aStack [ length ] === a ) { return bStack [ length ] === b ; } } // Add the first object to the stack of traversed objects. aStack . push ( a ) ; bStack . push ( b ) ; // Recursively compare objects and arrays. if ( areArrays ) { // Compare array lengths to determine if a deep comparison is necessary. length = a . length ; if ( length !== b . length ) { return false ; } // Deep compare the contents, ignoring non-numeric properties. while ( length -- ) { if ( ! eq ( a [ length ] , b [ length ] , aStack , bStack ) ) { return false ; } } } else { // Deep compare objects. var keys = Object . keys ( a ) , key ; length = keys . length ; // Ensure that both objects contain the same number of properties before comparing deep equality. if ( Object . keys ( b ) . length !== length ) { return false ; } while ( length -- ) { // Deep compare each member key = keys [ length ] ; if ( ! ( has ( b , key ) && eq ( a [ key ] , b [ key ] , aStack , bStack ) ) ) { return false ; } } } // Remove the first object from the stack of traversed objects. aStack . pop ( ) ; bStack . pop ( ) ; return true ; }
Internal recursive comparison function for `isEqual`.
Internal recursive comparison function for isEqual .