Loops

• Loops allows us to automate repetitive tasks

• Iterate is a generic term that means “to repeat” in the context of loops.

• A loop will continue to iterate until a specified condition, commonly known as a stopping condition, is met.

Types of Loops

For Loops

• A for loop declares looping instructions, with three important pieces of information separated by semicolons ;
• The initialization defines where to begin the loop by declaring
• The stopping condition determines when to stop looping

• The iteration statement updates the iterator each time the loop is completed

• Example

    for (int i = 0; i < 3; i++){
        console.log("your gay")
    }
  
    //output: your gay *4
  

• Reverse for Loop

  • The loop will index from the last element in the loop to the first through subtraction

  • This would irritate the loop in reverse

    const items = ['apricot', 'banana', 'cherry'];
    
    for (let i = items.length - 1; i >= 0; i -= 1) {
    console.log(`${i}. ${items[i]}`);
    }
    
    // Prints: 2. cherry
    // Prints: 1. banana
    // Prints: 0. apricot
    

• Nested for Loops

  • A nested for loop is when a for loop runs inside another for loop.

  • The inner loop will run all its iterations for each iteration of the outer loop.

  • Example

      for (let excercise = 1; excercise < 4; excercise ++) {
          console.log(`start excercise ${excercise}`)
          for (let rep = 1; rep < 3; rep ++) {
          conosle.log(`lifiting weight repetation ${rep}`)}
      }
    
      // output:
      start excercise 1
      lifiting weight repetation 1
      lifiting weight repetation 2
      lifiting weight repetation 3
      start excercise 2
      lifiting weight repetation 1
      lifiting weight repetation 2
      lifiting weight repetation 3
    

Looping Through Arrays

• An array’s length can be evaluated with the .length property.

• The .length of the array can be used as the stopping condition in the loop.

• Reading the array

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

• Filling an array

    const types = [];
  
    for (let i = 0; i < jonas.length; i++) {
        types.push(typeof jonas[i]);
    }
  

While Loops

• A while loop is a loop that keeps running as long as a specified condition is true

• Use while loop If you want the loop to break based on a condition other than the number of times it runs.

• Syntax

    while () {
    // code to be excuted
    }
  

  • between the () we write the condition
  • between the {} we write the actual code

• Example

    while (i < 6) {
      console.log(i);
      i++;
    }
  

• Infinite loop

  • by specifying a condition that is always true, we run an infinite loop

    while (true) {
      console.log("Hello, World!")
    }
    
    // this will print Hello, World! forever
    

Loop Control Statements

Continue

• The continue keyword exist the irritation of the loop if a condition is not met

    for (let i = 0; i < bayak.length; i++) {
        if (typeof bayak[i]) !== "string") continue;
        console.log(jonas[i], typeof jonas[i]);
    }
  

Break

• Unlike the continue keyword, the break keyword will stop the irritation of loop.

    for (let i = 0; i < bayak.length; i++) {
        if (typeof bayak[i]) !== "string") break;
        console.log(jonas[i], typeof jonas[i]);
    }