Array.prototype.subtract = function(...operands) {
	const ops = new Set(Array.prototype.concat(...operands));
	return this.filter(v => !ops.has(v));
};
['a', 'c', 'b'].subtract(['d', 'c', 'y']); // ["a", "b"]
['a', 'c', 'b'].subtract(['d', 'c', 'y'], ['b', 'c']); // ["a"]