Functions in Programming

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Questions and Answers

What is the data type of the variable txt4 after the execution of the given statements?

Boolean

Number

String (correct)

Null

What is the result of the expression '5' + 5 in JavaScript?

55 (correct)

Undefined

Error

What is the purpose of the conditional operator in JavaScript?

To perform arithmetic operations

To assign a value to a variable based on some condition (correct)

To declare a variable

To output a message to the user

What is the syntax to define a JavaScript function?

function functionname() Signup and view all the answers

What is the data type of the variable x after the statement 'x = 5 + 5'?

Number Signup and view all the answers

What is the purpose of logical operators in JavaScript?

To determine equality or difference between variables or values Signup and view all the answers

What is the purpose of the assignment operator in JavaScript?

To assign a value to a variable Signup and view all the answers

What is the data type of the variable x after the statement 'x = 5 + "5"'?

String Signup and view all the answers

What is the purpose of the return statement in a function?

To specify the value that a function should return Signup and view all the answers

What is the correct syntax for declaring a function with three parameters?

function functionName(parameter1, parameter2, parameter3) Signup and view all the answers

What is the output of the following code: document.write(product(4,3))?

16 Signup and view all the answers

What is the purpose of the if statement in JavaScript?

To execute a block of code only if a condition is true Signup and view all the answers

What is the correct syntax for an if statement in JavaScript?

if(condition) {code to be executed} Signup and view all the answers

What will happen if you use uppercase letters (IF) instead of lowercase letters (if) in an if statement?

The code will generate a JavaScript error Signup and view all the answers

What is the purpose of the switch statement in JavaScript?

To select one of many blocks of code to be executed Signup and view all the answers

What is the correct way to declare a variable in JavaScript?

var d = new Date(); var time = d.getHours(); Signup and view all the answers

What is a characteristic of JavaScript variable names?

They must begin with a letter, an underscore, or a dollar sign Signup and view all the answers

What is the scope of a variable declared within a JavaScript function?

Local Signup and view all the answers

What is the result of the expression `txt3=txt1+txt2` assuming `txt1='What a very'` and `txt2='nice day'`?

What a verynice day Signup and view all the answers

What is the purpose of assignment operators in JavaScript?

To assign values to variables Signup and view all the answers

What is the difference between local and global variables in JavaScript?

Local variables can only be accessed within a function, while global variables can be accessed anywhere Signup and view all the answers

What is the result of the expression `alert(' Global y = ' + y)` assuming `y=5`?

Global y = 5 Signup and view all the answers

What is the purpose of the `var` keyword in JavaScript?

To declare a local variable Signup and view all the answers

What is the result of the expression `txt4=txt1+' '+txt2` assuming `txt1='What a very'` and `txt2='nice day'`?

What a very nice day Signup and view all the answers

Study Notes

Functions in JavaScript

A function is a block of code designed to perform a particular task and can be executed by an event or by a call to the function.
A JavaScript function is defined with the function keyword, followed by a name, and then parentheses ().
Function names can contain letters, digits, underscores, and dollar signs (same rules as variables).

Function Syntax

function functionName(parameter1, parameter2, …) { code to be executed }

Return Statement

Functions that return a value must use the return statement.
Example: function product(a, b) { return a * b; }

Conditional Statements

if statement: executes code if a specified condition is true.
if...else statement: executes code if the condition is true and another code if the condition is false.
if...else if....else statement: selects one of many blocks of code to be executed.
switch statement: selects one of many blocks of code to be executed.

Conditional Statement Syntax

if (condition) { code to be executed if condition is true }

Example of if Statement

if (time < 12) { write a "Good morning" greeting }

Adding Strings and Numbers

When you add a number and a string, the result will be a string.

Examples of Adding Strings and Numbers

var x = 5 + 5;
document.write(x + "");
x = "5" + "5";
document.write(x + "");
x = 5 + "5";
document.write(x + "");
x = "5" + 5;
document.write(x + "");

Comparison Operators

Used in logical statements to determine equality or difference between variables or values.

Logical Operators

Used to combine conditions in logical statements.

Conditional Operator

Assigns a value to a variable based on some condition.
Syntax: variablename = (condition) ? value1 : value2;

Variables in JavaScript

Variable names are case sensitive.
Variable names must begin with a letter, an underscore (_), or a dollar sign ($).
Subsequent characters can be letters, digits, underscores, or dollar signs.

Local and Global Variables

Local variables: declared within a JavaScript function and can only be accessed within that function.
Global variables: declared outside a function and can be accessed by all scripts and functions on the web page.

Example of Local and Global Variables

function displaymessage() { var x = 3; alert("Local x = " + x + " , Global y=" + y); }
var y = 5; alert(" Global y = " + y);

Arithmetic Operators

Used for arithmetic operations such as addition, subtraction, multiplication, division, etc.

Assignment Operators

Used to assign values to JavaScript variables.

The + Operator

Can be used to add string variables or text values together.
Example: txt1 = "What a very"; txt2 = "nice day"; txt3 = txt1 + txt2; txt4 = txt1 + " " + txt2;

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Description

This quiz covers the basics of functions in programming, including the syntax and usage of function definitions and the return statement.