A function to fully compare objects and arrays.

compareObjectOrArray.js

const isEqual = (value, other) => {
  // Tests - same object type, same length, same items
  const type = Object.prototype.toString.call(value);
  
  if (type !== Object.prototype.toString.call(other)) {
    return false;
  }
  
  if (['[object Array]', '[object Object]'].indexOf(type) < 0) {
    return false;
  }
  
  const valueLen = type === '[object Array]' ? value.length : Object.keys(value).length;
  const otherLen = type === '[object Array]' ? other.length : Object.keys(other).length;
  if (valueLen !== otherLen) {
    return false;
  }
  
  if (type === '[object Array]') {
    for (let i = 0; i < valueLen; i++) {
      // Compare Item
      if (compare(value[i], other[i]) === false) {
        return false;
      }
    }
  } else {
    for (let key in value) {
      if (value.hasOwnProperty(key)) {
        // Compare item
        if(compare(value[key], other[key]) === false) {
          return false;
        }
      }
    }
  }
  

  // No tests failed, return true
  return true;
};

// Compare two items
const compare = (item1, item2) => {
  const itemType = Object.prototype.toString.call(item1);
  
  if (['[object Array]', '[object Object]'].indexOf(itemType) >= 0) {
    if (!isEqual(item1, item2)) {
      return false;
    }
  } else {
    if (itemType !== Object.prototype.toString.call(item2)) {
      return false;
    }
    
    if (itemType === '[object Function]') {
      if (item1.toString() !== item2.toString()) {
        return false;
      }
    } else {
      if (item1 !== item2) {
        return false;
      }
    }
  }
};