In programming languages, loops are a series of commands that are executed repeatedly until a designated condition is no longer met. This helps to streamline the code. Loops are commonly utilized with arrays. The general format of a loop statement is outlined below:
We can classify the loops into two types:
- Indefinite
- Definite
Indefinite Loop
Indefinite loops are characterized by the uncertainty of the number of iterations prior to the commencement of the statement block's execution. There are two types of indefinite loops:
- while loop
- do-while loop
TypeScript while loop
The TypeScript while loop allows for the repetition of elements an infinite number of times. It continues to execute the provided instructions as long as the defined condition remains true. This construct is particularly useful when the total number of iterations is uncertain. Below is the syntax for the while loop.
Syntax
while (condition)
{
//code to be executed
}
The explanation of while loop syntax is:
A while loop initiates its operation by assessing the condition. When the condition is true, the statements within the loop body are executed. If the condition is false, the execution moves to the first statement that follows the loop. The loop concludes when the condition evaluates to false, marking the end of the loop's life cycle.
Example
let num = 4;
let factorial = 1;
while(num >=1) {
factorial = factorial * num;
num--;
}
console.log("The factorial of the given number is: "+factorial);
Output:
TypeScript do-while loop
The TypeScript do-while loop allows for repeated execution of its elements an infinite number of times, much like the while loop. However, it differs in one key aspect: it guarantees execution at least once, regardless of whether the condition evaluates to true or false. It is advisable to utilize a do-while loop when the number of iterations is unspecified and at least one execution of the loop is necessary. The syntax for the do-while loop is provided below.
Syntax
do{
//code to be executed
}while (condition);
The explanation of do-while loop syntax is:
The do-while loop executes the statement initially without evaluating any condition. Following the execution of the statement and the update of the variable, the condition is then assessed. If the condition evaluates to true, the loop proceeds to the next iteration. Conversely, if the condition evaluates to false, the loop terminates, concluding its lifecycle.
Example
let n = 10;
do {
console.log(n);
n++;
} while(n<=15);
Output:
