How to create a function in JavaScript?
Select one
A. function.myFunction()
B. function myFunction()
C. function = myFunction()
D. declare function myFunction()
Answers
Answer:
Declare a function and output "Hello World" in an element with id="demo", when the function is called:
function myFunction() { // Declare a function
document.getElementById("demo").innerHTML = "Hello World!";
}
myFunction(); // Call the function
More "Try it Yourself" examples below.
Definition and Usage
The function statement declares a function.
A declared function is "saved for later use", and will be executed later, when it is invoked (called).
In JavaScript, functions are objects, and they have both properties and methods.
A function can also be defined using an expression (See Function Definitions).
Read our JavaScript Tutorial to learn all you need to know about functions. Start with the introduction chapter about JavaScript Functions and JavaScript Scope. For more detailed information, see our Function Section on Function Definitions, Parameters, Invocation and Closures.
Tip: Use the return statement to return a value from the function.
Browser Support
Statement
function Yes Yes Yes Yes Yes
Syntax
function functionName(parameters) {
code to be executed
}
Parameter Values
Parameter Description
functionName Required. Specifies the name of the function, which can be "saved for later use". Function names can contain letters, digits, underscores, and dollar signs (same rules as variables)
parameters Optional. Specifies a set of zero or more parameter names, separated by commas.
Function parameters are the names listed in the function definition.
Function arguments are the real values received by the function when it is invoked. Inside the function, the arguments are used as local variables.
Note: If a function is called with a missing argument, the value of the missing argument is set to undefined
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Explanation:
function myFunction() {
return Math.PI;
}
Example
Return the product of a and b:
function myFunction(a, b) {
return a * b;
}
Example
With functions, you can use the same code many times with different arguments, to produce different results.
Convert Fahrenheit to Celsius:
function toCelsius(fahrenheit) {
return (5/9) * (fahrenheit-32);
}
Example
Functions can be used as variables.
Instead of:
temp = toCelsius(32);
text = "The temperature is " + temp + " Centigrade";
You can use:
text = "The temperature is " + toCelsius(32) + " Centigrade";
Example
JavaScript functions have a built-in object called the arguments object.
The arguments.length property returns the number of arguments received when the function was invoked:
function myFunction(a, b) {
return arguments.length;
}
Example
Click on a button to call a function, which will output "Hello World" in an element with id="demo":
<button onclick="myFunction()">Click me</button>
<p id="demo"></p>
Answer:
c:- function= myfunction()
Explanation:
JavaScript is a scripting language used along with HTML and CSS to make the website interactive along. It is used both on the client-side and server-side.
To create a function, we must first declare it and give it a name, the same way we'd create any variable, and then we follow it by a function definition: var sayHello = function() { }; We could put any code inside that function - one statement, multiple statements - depends on what we want to do.
Ways to create a function :-
Use the keyword function followed by the name of the function.
After the function name, open and close parentheses.
After parenthesis, open and close curly braces.
Within curly braces, write your lines of code.