**Introduction to Loops**
Loops are a fundamental concept in programming that allow us to execute a block of code repeatedly for a specified number of times or until a certain condition is met. In this article, we will explore the basics of loops, including types of loops, how to use them, and examples of different loop structures.
**Pushing Zero onto an Array**
One common type of loop is the `for` loop, which allows us to execute a block of code repeatedly for a specified number of times. In this example, we have an array variable `r`, which contains numbers from 0 to 4. We want to push these numbers onto another array. To do this, we initialize a variable `i` to 0 and use the `for` loop to execute a block of code that pushes each number onto the array. The loop will continue until `i` is greater than or equal to the length of the array.
`// Initialize i to 0`
`let i = 0;`
`// Loop through the array and push numbers onto another array`
for (let r of [0, 1, 2, 3, 4]) {
// Push each number onto the array
push(r);
}
**Incrementing a Variable**
After we have pushed all the numbers onto the array, we need to increment `i` to move on to the next iteration of the loop. This is done using the increment operator `++`. In this case, after we finish executing the block of code for each number, we will increment `i` by 1.
`// Increment i by 1`
`i++;`
**Breaking Out of a Loop**
Another common use of loops is to break out of them early. This can be done using the `break` statement. In this example, we want to break out of the loop as soon as `i` is greater than 2. We add the `break` statement after the increment operator.
`// Use the break statement to exit the loop`
for (let r of [0, 1, 2, 3, 4]) {
// Push each number onto the array
push(r);
if (i > 2) {
// Break out of the loop
break;
}
}
**Iterating Through an Array**
Loops can also be used to iterate through arrays. In this example, we have an array `r` and we want to console.log each item in it. We initialize a variable `i` to 0 and use the `for` loop to execute a block of code that console.log's each item in the array.
`// Initialize i to 0`
`let i = 0;`
`// Loop through the array and console.log each item`
for (let r of [1, 2, 3, 4]) {
// Console.log each item
console.log(r);
// Increment i by 1
`i++;`
}
**Nested For Loops**
When we have multi-dimensional arrays, we can use nested for loops to iterate through both the array and any subarrays. In this example, we have a nested array with three inner arrays. We want to console.log each item in the outer array, as well as each item in the inner arrays.
`// Initialize i to 0`
`let i = 0;`
`// Loop through the outer array`
for (let r of [1, 2, 3]) {
`// Initialize J to 0`
let j = 0;
`// Loop through the inner arrays`
for (let s of r) {
// Console.log each item
console.log(s);
// Increment J by 1
`j++;`
}
// Increment i by 1
`i++;`
}
**Conclusion**
In conclusion, loops are a fundamental concept in programming that allow us to execute a block of code repeatedly for a specified number of times or until a certain condition is met. We have explored the basics of loops, including types of loops, how to use them, and examples of different loop structures. With these concepts under our belt, we can now write more complex programs that manipulate arrays and perform calculations.