deep equal js

deep_equal.js

function deepEq( x, y, propertyList, pred ) {
  if ( x === y ) return true;
    // if both x and y are null or undefined and exactly the same

  if ( ! ( x instanceof Object ) || ! ( y instanceof Object ) ) return false;
    // if they are not strictly equal, they both need to be Objects

  if ( x.constructor !== y.constructor ) return false;
    // they must have the exact same prototype chain, the closest we can do is
    // test there constructor.

	if (propertyList){
		for (var p in propertyList){
			if (!x.hasOwnProperty(p)^!y.hasOwnProperty(p)) return false
			// if (!y.hasOwnProperty(p)) return false
			if (x[p]===y[p]) continue
			if (typeof(x[p]!=='object')) return false
			if (!deepEq(x[p], y[p])) return false
		}
	} else {
		var pred_tmp;
		for ( var p in x ) {

			if (pred){
				pred_tmp = pred(x[p],y[p],x,y,p)
				if (pred_tmp===false) return false;
				else if (pred_tmp===true) continue;
			}

			if ( ! x.hasOwnProperty( p ) ) continue;
				// other properties were tested using x.constructor === y.constructor

			if ( ! y.hasOwnProperty( p ) ) return false;
				// allows to compare x[ p ] and y[ p ] when set to undefined

			if ( x[ p ] === y[ p ] ) continue;
				// if they have the same strict value or identity then they are equal

			if ( typeof( x[ p ] ) !== "object" ) return false;
				// Numbers, Strings, Functions, Booleans must be strictly equal

			if ( ! deepEq( x[ p ],  y[ p ] ) ) return false;
				// Objects and Arrays must be tested recursively
		}

		for ( p in y ) {
			if ( y.hasOwnProperty( p ) && ! x.hasOwnProperty( p ) ) return false;
				// allows x[ p ] to be set to undefined
		}
	}

  return true;
}