How does constructor differ from normal function

Aug, Normal Functions are those which we have to call But there is no need to call Constructer 1. Feb, 5. Jan, Dec, Nov, Oct, 3. Difference between them? Aug, 7. Constructor does not a have return type but function having a return type and it can be return the values one by one 1. May, May, 8. Apr, Constructor does not have any return type but member function is a return type.

Mar, 8. If we use a readonly string in class then constructor can change the value of string but a normal function can not change it's value 1. Developer Programmer Sr. Developer Sr. Why do you want to leave your current company? Next Constructors in Java. Recommended Articles. Article Contributed By :. Easy Normal Medium Hard Expert. Writing code in comment?

Please use ide. Load Comments. What's New. Most popular in Difference Between. Sometimes you'd need to supply the method as a callback, for example to setTimeout or an event listener. In such cases, you might encounter difficulties accessing this value. For example, let's use use logName method as a callback to setTimeout :. After 1 second, undefined is logged to console. That's when the method is separated from the object. Now you're sure that the method doesn't lose the context. Binding this manually requires boilerplate code, especially if you have lots of methods.

There's a better way: the arrow functions as a class field. Thanks to Class fields proposal at this moment at stage 3 you can use the arrow function as methods inside classes. Now, in contrast with regular functions, the method defined using an arrow binds this lexically to the class instance. Now you can use batman. The value of this inside logName method is always the class instance:. Understanding the differences between regular and arrow functions helps choose the right syntax for specific needs.

But this inside the arrow function is bound lexically and equals to this of the outer function. The arrow function, on the opposite, doesn't define arguments but you can easily access the arrow function arguments using a rest parameter If the arrow function has one expression, then the expression is returned implicitly, even without using the return keyword.

Last but not least, you can define methods using the arrow function syntax inside classes. Fat arrow methods bind this value to the class instance. Anyhow the fat arrow method is invoked, this always equals the class instance, which is useful when the methods are used as callbacks. Start discussion. You can define JavaScript functions in many ways.

The first, usual way, is by using the function keyword: javascript.