The JavaScript function is a set of statements that take inputs, do some specific computation, and produce output. Basically, a function is a set of statements that performs some tasks or does some computation and then return the result to the user.
Syntax:
function functionName(Parameter1, Parameter2, ..) {
// Function body
}
Example: Below is a sample program that illustrates the working of functions in JavaScript:
Javascript
function welcomeMsg(name) {
console.log("Hello " + name
+ " welcome to GeeksforGeeks");
}
let nameVal = "Admin";
welcomeMsg(nameVal);
|
Output:
Hello Admin welcome to GeeksforGeeks
The Complete List of JavaScript Functions & Properties are listed below:
JavaScript Function Parameters:
Parameters | Description | Example |
|---|
| Function | The function definition and real values passed to the function in the function definition are known as arguments. |
|
| Rest | Improved way to handle function parameters defined, allowing us to more easily handle various inputs as parameters in a function. |
|
| Default parameters | In JavaScript, the parameters of functions default to undefined. However, in some situations, it might be useful to set a different default value. |
|
JavaScript Functions Properties:
Properties
| Description | Example
|
|---|
| length | Return the number of parameters required by a function. |
|
| displayName | Set the display name of the function. |
|
| caller | Returns the function that invoked the specified function. |
|
| name | Return the name of the function. |
|
JavaScript Functions:
Functions
| Description | Example
|
|---|
| apply() | It is different from the function call() because it takes arguments as an array. |
|
| isFinite() | It returns true for all the values except +infinity, -infinity, or NaN. |
|
| isNaN() | It returns true if the value is a NaN else returns false. |
|
| unescape() | It decodes that string encoded by the escape() function. |
|
| escape() | It can be transmitted to any computer in any network which supports ASCII characters. |
|
| number() | Convert the data type to a number. |
|
| map() | The calling function for each and every array element in an array. |
|
| String() | Convert the value of an object to a string value. |
|
| eval() | If the argument represents one or more JavaScript statements, eval() evaluates the statements. |
|
| uneval() | Create a string representation of the source code of an Object. |
|
| parseInt() | Accept the string and radix parameters and convert them into an integer. |
|
| parseFloat() | Accept the string and convert it into a floating-point number. |
|
| console.log() | To print any kind of variables defined before in it or to just print any message that needs to be displayed to the user. |
|
Basics of Functions:
JavaScript Operations on Function
| Description | Example
|
|---|
| Function Generator | It needs to generate a value, it does so with the yield keyword rather than return. |
|
| Function Binding | In JavaScript, function binding happens using bind() method. |
|
| Function Invocation | It is common to use the term “call a function” instead of “invoke a function”. |
|
| Function Expression | Create an anonymous function that doesn’t have any function name. |
|
| Arrow Functions | Provide generator functions with a concise way to write functions in JavaScript. |
|
| Async Function | It checks that we are not breaking the execution thread. |
|
| Pure Functions | Returns the same result if the same arguments are passed. |
|
| Nested Functions | Return is a combination of the output from the outer as well as the inner function(nested function). |
|
Last Updated :
24 May, 2023
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