For Loop

The for loop is the most basic loop that repeatedly executes a block of code as long as the given condition is true.

Copy
for (initialization; condition; update) {
  // Code to be executed repeatedly
}

• Initialization: An expression that is executed once when the loop starts. It is usually used to initialize a variable for the loop.

• Condition: This condition is checked before each iteration. If it is true, the code block enclosed in curly braces ({ }) is executed. If it is false, the loop stops executing.

• Update: An expression that is executed after each iteration of the block of code. It is often used to increase the value of the loop variable. The increment operator ++ or decrement operator -- are commonly used.

The for loop will keep executing the code until the specified condition becomes false.

The variable used for initialization, condition, and update is conventionally named i for "index."

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for (let i = 0; i < 3; i++) {
  // let i = 0 : initialization
  // i < 3 : condition
  // i++ : update
}

1. Printing numbers from 0 to 4

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for (let i = 0; i < 5; i++) {
  console.log(i); // Prints 0, 1, 2, 3, 4
}

2. Printing all elements in an array

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const fruits = ['Apple', 'Banana', 'Cherry'];

for (let i = 0; i < fruits.length; i++) {
  console.log(fruits[i]); // Prints "Apple", "Banana", "Cherry" in order
}

3. Printing numbers from 5 to 1 in reverse order

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for (let i = 5; i > 0; i--) {
  console.log(i); // Prints 5, 4, 3, 2, 1
}