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JavaScript for Loop

What is the for Loop?

The for loop is used to execute a block of code a specific number of times. It is commonly used for iterating over arrays or executing code repeatedly based on a condition.

Syntax

for (initialization; condition; increment) {
    // Code to execute
}
  • Initialization: Runs once before the loop starts, typically used to declare a loop counter.
  • Condition: Evaluated before each iteration. If it evaluates to true, the loop continues; if false, the loop stops.
  • Increment: Executes after each iteration, usually to update the loop counter.

Example: Basic for Loop

for (let i = 0; i < 5; i++) {
    console.log('Iteration: ' + i);
}

Output:

Iteration: 0
Iteration: 1
Iteration: 2
Iteration: 3
Iteration: 4

Using the for Loop with Arrays

const fruits = ['apple', 'banana', 'cherry'];

for (let i = 0; i < fruits.length; i++) {
    console.log(fruits[i]);
}

Output:

apple
banana
cherry

Example: Summing Numbers

let sum = 0;

for (let i = 1; i <= 10; i++) {
    sum += i;
}
console.log('Sum: ' + sum);

Output:

Sum: 55

Nested for Loops

for (let i = 0; i < 3; i++) {
    for (let j = 0; j < 2; j++) {
        console.log('i: ' + i + ', j: ' + j);
    }
}

Output:

i: 0, j: 0
i: 0, j: 1
i: 1, j: 0
i: 1, j: 1
i: 2, j: 0
i: 2, j: 1

When to Use the for Loop

The for loop is ideal for scenarios where you know the number of iterations in advance, such as processing arrays or executing a block of code a fixed number of times.

Conclusion

The for loop is a fundamental control structure in JavaScript that allows you to efficiently repeat code. Understanding how to use it effectively can enhance your coding skills.

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