Understanding Object.freeze() in javascript. This tutorial explains how to freeze an object in javascript, so that object can't be modified further. The Object.freeze() method freezes an object: that is, prevents new properties from being added to it; prevents existing properties from being removed; and prevents existing properties, or their enumerability, configurability, or writability, from being changed, it also prevents the prototype from being changed. The method returns the object in a frozen state.