javascript

array-methods

Array Methods

The Array object, as with arrays in other programming languages, enables storing a collection of multiple items under a single variable name, and has members for performing common array operations.

Array Length

If you are having an arrays of items, and you want to know how many items there are, you can use .length

const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.length); // 4

Array toString()

It will convert an array to a string with comma separated.

const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.toString()); // Afghanistan,America,Japan,Russia

Array pop()

It will remove the last item from an array.

const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.pop()); // ["Afghanistan", "America", "Japan"]

Array push()

It will add many items to the ending of an array.

const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.push("Thailand", "Italia"));
 
// ["Afghanistan", "America", "Japan", "Russia", "Thailand", "Italia"];

Array shift()

It will remove the first item of an array.

const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.shift()); // ["America", "Japan", "Russia"]

Array unShift()

It will add many items to the beginning of an array.

const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.unShift("Thailand", "Italia"));
 
// ["Thailand", "Italia", "Afghanistan", "America", "Japan", "Russia"]

Array concat()

If we are having several arrays and we want to combine them together and make them into one array, we can use concat().

const group1 = ["Ali", "Alex", "Ahmad"];
const group2 = ["Bob", "Bobby", "Bonnie"];
const group3 = ["Connor", "Charlie"];
 
const groups = group1.concat(group2, group3);
 
// => ["Ali", "Alex", "Ahmad", "Bob", "Bobby", "Bonnie", "Connor", "Charlie"]

We can replace the position of each array by especifing them first.

const group1 = ["Ali", "Alex", "Ahmad"];
const group2 = ["Bob", "Bobby", "Bonnie"];
const group3 = ["Connor", "Charlie"];
 
const groups = group3.concat(group1, group2);
 
// => ["Connor", "Charlie", "Ali", "Alex", "Ahmad", "Bob", "Bobby", "Bonnie"]

Array slice()

You can use this method If you are looking to delete the first several items.

const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.slice(1)); // ["America", "Japan", "Russia"]
console.log(name.slice(2)); // ["Japan", "Russia"]
console.log(name.slice(3)); // ["Russia"]
console.log(name.slice(4)); // []

Array splice()

You can delete several items, find a position and add your items.

const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.splice(2, 0, "Italia")); // ["Afghanistan", "America", "Italia", "Japan", "Russia"]
  • First parameter says a position that you can add your new items.
  • Second parameter defines how many items should be removed.
  • The rest parameter defines your new items.
const name = ["Afghanistan", "America", "Japan", "Russia"];
 
console.log(name.splice(2, 1, "Italia", "Thailand"));
 
// ["Afghanistan", "America", "Italia", "Thailand", "Russia"]