Conditional Statements
Conditional statements are those where a block of code is executed based on the result of a condition or an expression.
In JavaScript, we have following conditional statements.
- if – statement is used to conditionally execute a block of code.
- if-else – statement is used to conditionally execute one of the two code blocks.
- if-else-if – statement is used to implement a conditional ladder, to execute one of the two or more code blocks.
- switch-case – statement is used to execute a block of code whose value matches with the given expression.
Examples
if statement
a = 10
if (a > 0) {
console.log(`${a} is a positive number`);
}
if-else statement
a = -9
if (a > 0) {
console.log(`${a} is a positive number`);
} else {
console.log(`${a} is not a positive number`);
}
if-else-if statement
a = -9
if ( a > 0 ) {
console.log(`${a} is a positive number`);
} else if ( a < 0 ) {
console.log(`${a} is a negative number`);
} else {
console.log(`a is zero`);
}
switch-case statement
a = 2
switch (a) {
case 0:
console.log("zero");
break;
case 1:
console.log("one");
break;
case 2:
console.log("two");
break;
case 3:
console.log("three");
break;
case 4:
console.log("four");
break;
default:
console.log("unknown number");
}