If statement:
1. Purpose: The if statement allows you to execute a block of code if a specified condition is true.
syntax:
if(condition)
{
//code if the condition is true
}
2. example:
<script>var temperature = 25;
if (temperature > 20)
{
document.write("It's a warm day!"); // code to execute if the condition is true
}
</script>
3. Explanation: In this example, if the value of the variable temperature is greater than 20, the message "It's a warm day!" will be printed to the console.
If-else statement:
1. Purpose: The if-else statement provides an alternative code block to execute if the condition in the if statement is false.
syntax:
if(condition)
{
//code if the condition is true
}
else
{
code if the condition is false
}
2. example:
<script>
var time = 10;
if (time < 12) {
document.write("Good morning!"); // code to execute if the condition is true
} else {
document.write("Good afternoon!"); // code to execute if the condition is false
}
</script>
3. Explanation: In this example, if the value of the variable time is less than 12, the message "Good morning!" will be printed to the console. Otherwise, if the condition is false (time is not less than 12), the message "Good afternoon!" will be printed.
If-else if statement:
1. Purpose: The if-else if statement allows you to check multiple conditions and execute different blocks of code based on them.
example:
if(condition1)
{
//code if condition1 is true
}
else if(condition2)
{
//code if condition2 is true
}
else if(condition3)
{
//code if condition3 is true
}
else
{
//code if all conditions are false
}
2. example:
<script>
var score = 75;
if (score >= 90) {
document.write("Grade: A"); // code to execute if condition1 is true
} else if (score >= 80) {
document.write("Grade: B"); // code to execute if condition2 is true
} else if (score >= 70) {
document.write("Grade: C"); // code to execute if condition3 is true
} else {
document.write("Grade: D"); // code to execute if none of the conditions are true
}
</script>
3. Explanation: In this example, the variable score is evaluated against multiple conditions. If the score is greater than or equal to 90, "Grade: A" is printed. If the score is not greater than or equal to 90 but is greater than or equal to 80, "Grade: B" is printed, and so on. If none of the conditions are true, "Grade: D" is printed.
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