function eq()

in packages/expect-utils/src/jasmineUtils.ts [65:205]

• 106 lines of code
• 46 McCabe index (conditional complexity)

function eq(
  a: any,
  b: any,
  aStack: Array<unknown>,
  bStack: Array<unknown>,
  customTesters: Array<Tester>,
  strictCheck: boolean | undefined,
): boolean {
  var result = true;

  var asymmetricResult = asymmetricMatch(a, b);
  if (asymmetricResult !== undefined) {
    return asymmetricResult;
  }

  for (var i = 0; i < customTesters.length; i++) {
    var customTesterResult = customTesters[i](a, b);
    if (customTesterResult !== undefined) {
      return customTesterResult;
    }
  }

  if (a instanceof Error && b instanceof Error) {
    return a.message == b.message;
  }

  if (Object.is(a, b)) {
    return true;
  }
  // A strict comparison is necessary because `null == undefined`.
  if (a === null || b === null) {
    return a === b;
  }
  var className = Object.prototype.toString.call(a);
  if (className != Object.prototype.toString.call(b)) {
    return false;
  }
  switch (className) {
    case '[object Boolean]':
    case '[object String]':
    case '[object Number]':
      if (typeof a !== typeof b) {
        // One is a primitive, one a `new Primitive()`
        return false;
      } else if (typeof a !== 'object' && typeof b !== 'object') {
        // both are proper primitives
        return Object.is(a, b);
      } else {
        // both are `new Primitive()`s
        return Object.is(a.valueOf(), b.valueOf());
      }
    case '[object Date]':
      // Coerce dates 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;
    // RegExps are compared by their source patterns and flags.
    case '[object RegExp]':
      return a.source === b.source && a.flags === b.flags;
  }
  if (typeof a !== 'object' || typeof b !== 'object') {
    return false;
  }

  // Use DOM3 method isEqualNode (IE>=9)
  if (isDomNode(a) && isDomNode(b)) {
    return a.isEqualNode(b);
  }

  // Used to detect circular references.
  var length = aStack.length;
  while (length--) {
    // Linear search. Performance is inversely proportional to the number of
    // unique nested structures.
    // circular references at same depth are equal
    // circular reference is not equal to non-circular one
    if (aStack[length] === a) {
      return bStack[length] === b;
    } else if (bStack[length] === b) {
      return false;
    }
  }
  // Add the first object to the stack of traversed objects.
  aStack.push(a);
  bStack.push(b);
  // Recursively compare objects and arrays.
  // Compare array lengths to determine if a deep comparison is necessary.
  if (strictCheck && className == '[object Array]' && a.length !== b.length) {
    return false;
  }

  // Deep compare objects.
  var aKeys = keys(a, hasKey),
    key;

  var bKeys = keys(b, hasKey);
  // Add keys corresponding to asymmetric matchers if they miss in non strict check mode
  if (!strictCheck) {
    for (var index = 0; index !== bKeys.length; ++index) {
      key = bKeys[index];
      if ((isAsymmetric(b[key]) || b[key] === undefined) && !hasKey(a, key)) {
        aKeys.push(key);
      }
    }
    for (var index = 0; index !== aKeys.length; ++index) {
      key = aKeys[index];
      if ((isAsymmetric(a[key]) || a[key] === undefined) && !hasKey(b, key)) {
        bKeys.push(key);
      }
    }
  }

  // Ensure that both objects contain the same number of properties before comparing deep equality.
  var size = aKeys.length;
  if (bKeys.length !== size) {
    return false;
  }

  while (size--) {
    key = aKeys[size];

    // Deep compare each member
    if (strictCheck)
      result =
        hasKey(b, key) &&
        eq(a[key], b[key], aStack, bStack, customTesters, strictCheck);
    else
      result =
        (hasKey(b, key) || isAsymmetric(a[key]) || a[key] === undefined) &&
        eq(a[key], b[key], aStack, bStack, customTesters, strictCheck);

    if (!result) {
      return false;
    }
  }
  // Remove the first object from the stack of traversed objects.
  aStack.pop();
  bStack.pop();

  return result;
}