Notes on JS Array Loops
There are several ways to loop through an array in JavaScript:for loop: The most common and traditional way of looping through an array is using a for loop, which iterates over the array from the first element to the last element.
Example:
const arr = [1, 2, 3, 4, 5];
for (let i = 0; i < arr.length; i++) {
console.log(arr[i]);
}
for...of loop: A simpler way of iterating over an array is using the for...of loop, which is designed to loop through iterable objects like arrays.
Example:
const arr = [1, 2, 3, 4, 5];
for (let item of arr) {
console.log(item);
}
forEach() method: The forEach() method is a built-in method of an array that executes a provided function once for each array element.
Example:
const arr = [1, 2, 3, 4, 5];
arr.forEach(function(item) {
console.log(item);
});
const arr = [1, 2, 3, 4, 5];
arr.forEach(item => console.log(item));
map() method: The map() method creates a new array with the results of calling a provided function on every element in the original array.
Example:
const arr = [1, 2, 3, 4, 5];
const newArr = arr.map(function(item) {
return item * 2;
});
console.log(newArr);
filter() method: The filter() method creates a new array with all elements that pass the test implemented by the provided function.
Example:
const arr = [1, 2, 3, 4, 5];
const filteredArr = arr.filter(function(item) {
return item % 2 === 0;
});
console.log(filteredArr);
reduce() method: The reduce() method applies a function against an accumulator and each element in the array to reduce it to a single value.
Example:
const arr = [1, 2, 3, 4, 5];
const sum = arr.reduce(function(acc, item) {
return acc + item;
}, 0);
console.log(sum);