What are default values in JavaScript?

In JavaScript, function parameters default to undefined . However, it’s often useful to set a different default value. This is where default parameters can help. In the past, the general strategy for setting defaults was to test parameter values in the function body and assign a value if they are undefined .

Can you assign the default values to a function parameters?

It is called default function parameters . It allows formal parameters to be initialized with default values if no value or undefined is passed.

Is node JS asynchronous by default?

Node. js uses callbacks, being an asynchronous platform, it does not wait around like database query, file I/O to complete.

How can we set default value to the variable?

You can set the default values for variables by adding ! default flag to the end of the variable value. It will not re-assign the value, if it is already assigned to the variable.

What is a default parameter value?

The default parameter is a way to set default values for function parameters a value is no passed in (ie. it is undefined ). In a function, Ii a parameter is not provided, then its value becomes undefined . In this case, the default value that we specify is applied by the compiler.

What is arguments in JS?

arguments is an object that is accessible inside functions that contain the values of the arguments passed to that function. The arguments objects contain all of the arguments passed during the function call, even if there are not as many parameters in the function declaration. …

What is default parameter value?

What are the default values if we don’t give any value to restrict?

When no value is passed into a function the value of the parameter will be undefined . Using OR however means that the default value is used even when a valid falsy value is passed into the function.

Is js synchronous or asynchronous?

7 Answers. JavaScript is always synchronous and single-threaded. If you’re executing a JavaScript block of code on a page then no other JavaScript on that page will currently be executed. JavaScript is only asynchronous in the sense that it can make, for example, Ajax calls.

Do functions in JavaScript necessarily return a value?

No; Javascript functions are not required to return a value. If you call a function that doesn’t return a value, you’ll get undefined as the return value. Same goes for functions that has return; in them. And functions that can exit with out executing one of its returns.

What is the default return value of a function?

The default return value from a function is int. In other words, unless explicitly specified the default return value by compiler would be integer value from function.

What is a self-executing function in JavaScript?

A self executing function in JavaScript is the one which is invoked automatically as soon as it is defined. It’s an anonymous function and is usually used in conjunction to onload event.

What is the purpose of a self-executing function in JavaScript?

– It’s about defining and executing a function all at once. – You could have that self-executing function return a value and pass the function as a param to another function. – It’s good for encapsulation. – It’s also good for block scoping. – Yeah, you can enclose all your .js files in a self-executing function and can prevent global namespace pollution. 😉