In this topic, we will discuss the Nested if statement in Typescript.
The else…if ladder is useful to test multiple conditions. Its syntax is given below −
Syntax
if (boolean_expression1) {
//statements if the expression1 evaluates to true
} else if (boolean_expression2) {
//statements if the expression2 evaluates to true
} else {
//statements if both expression1 and expression2 result to false
}
When using if…else…if and else statements, there are a few points to keep in mind.
- An if can have zero or one else’s and it must come after any else..if‘s.
- An if can have zero to many else..if‘s and they must come before the else.
- Once an else..if succeeds, none of the remaining else..if‘s or else‘s will be tested.
Example: else…if ladder
var num:number = 2
if(num > 0) {
console.log(num+" is positive")
} else if(num < 0) {
console.log(num+" is negative")
} else {
console.log(num+" is neither positive nor negative")
}
The snippet displays whether the value is positive, negative or zero.
On compiling, it will generate the following JavaScript code −
//Generated by typescript 1.8.10
var num = 2;
if (num > 0) {
console.log(num + " is positive");
} else if (num < 0) {
console.log(num + " is negative");
} else {
console.log(num + " is neither positive nor negative");
}
Here is the output of the above code −
2 is positive
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