![Javascript forEach() Method](/_next/image?url=https%3A%2F%2Fapi.onjsdev.com%2Fuploads%2Feb655201_4323_4607_9c87_2530ee99695f_b9ffae3944.jpeg&w=640&q=75)
How To Use Javascript forEach() Method
By onjsdev
Jan 24th, 2024
JavaScript forEach() is an array method that iterates through an array and executes a callback function on each element in the array.
Syntax
The javascript forEach() method takes a callback function as its parameter:
array.forEach(callback);
A callback function also takes three parameters, including:
currentElement
: The current element being processedindex
: The index of the current element in the arrayarr
: The original array itself (array) .
A callback function can be defined as a named, anonymous, or arrow function:
const array = [1,2,3,4,5]
// Using a named function:
function callback(currentElement,index,arr) {
console.log(currentElement);
}
array.forEach(callback);
// Using an anonymous function:
array.forEach(function(currentElement, index, arr) {
console.log(currentElement);
});
// Using an arrow function:
array.forEach((currentElement, index, arr) => {
console.log(currentElement);
});
Examples
In the following example, we use the forEach()
method to iterate through the array of numbers and print each number and their indexes to the console using the console.log()
method.
const numbers = [1, 2, 3, 4, 5];
numbers.forEach(function(number, index) {
console.log(`Index: ${index}, Number: ${number}`);
});
/*
Index: 0, Number: 1
Index: 1, Number: 2
Index: 2, Number: 3
Index: 3, Number: 4
Index: 4, Number: 5
*/
In another example, to sum all the values in the array, we use the forEach method to iterate through each item in the array and add each value to the sum variable.
At the end, the sum
variable will contain the total sum of all the values in the array.
const values = [1, 2, 3, 4, 5];
let sum = 0;
values.forEach(value => {
sum += value;
});
console.log(sum); // Output: 15
Conclusion
In conclusion, the Javascript forEach method is a powerful method while working on arrays. It gets a callback function as an parameter and call this callback function for each element to perform actions over the elements.
If you want to learn more javascript array methods, you can take a look at the following guides:
Thank you for reading.