As opposed to Java, JavaScript is relatively easy to learn. One reason for this is the need of explicit type definitions for variables, parameters and return values in Java, which are not needed in JavaScript.
Both Java and JavaScript are “object-oriented” programming languages, but JavaScript is even more “object-oriented” than Java, which is rather “class-oriented”. There is no explicit class concept in JavaScript. Classes have to be defined in the form of special objects. However, objects can also be created without instantiating a class, and properties as well as methods can be defined for specific objects independently of any class definition.
At run time, properties and methods can be added to, or removed from, any object and class. While JavaScript classes can be redefined at runtime, immediately affecting all objects that instantiate the class, Java classes cannot be redefined in such a way.
JavaScript allows defining methods that are specific for an object, independently of its class. The methods of a Java object are defined for its class, it is not possible to define object-specific methods.
JavaScript has better support for functional programming. For instance, it supports “closures”, which are function execution contexts. Java only supports a limited version of closures for anonymous classes and “lambdas”.
