JavaScript Functions
JavaScript functions are used to perform operations. We can call JavaScript function many times to reuse the code.
Advantage of JavaScript function
There are mainly two advantages of JavaScript functions.
- Code reusability: We can call a function several times so it save coding.
- Less coding: It makes our program compact. We don’t need to write many lines of code each time to perform a common task.
JavaScript Function Syntax
The syntax of declaring function is given below.
JavaScript Functions can have 0 or more arguments.
JavaScript Function Example
Let’s see the simple example of function in JavaScript that does not has arguments.
Output of the above example
JavaScript Function Arguments
We can call function by passing arguments. Let’s see the example of function that has one argument.
Output of the above example
Function with Return Value
We can call function that returns a value and use it in our program. Let’s see the example of function that returns value.
Output of the above example
JavaScript Function Object
In JavaScript, the purpose of Function constructor is to create a new Function object. It executes the code globally. However, if we call the constructor directly, a function is created dynamically but in an unsecured way.
Syntax
Parameter
arg1, arg2, …. , argn – It represents the argument used by function.
functionBody – It represents the function definition.
JavaScript Function Methods
Let’s see function methods with description.
| Method | Description |
|---|---|
| apply() | It is used to call a function contains this value and a single array of arguments. |
| bind() | It is used to create a new function. |
| call() | It is used to call a function contains this value and an argument list. |
| toString() | It returns the result in a form of a string. |
JavaScript Function Object Examples
Example 1
Let’s see an example to display the sum of given numbers.
Output:
7
Example 2
Let’s see an example to display the power of provided value.
Output:
8