Arrays in JavaScript
Arrays properties and methods in JavaScript
length property of array in JavaScript
This property counts the length of array elements present in the array.
var arr=[10,20,30,40,50];
document.write("length of array is = "+arr.length);
Output:
The code above will display :
delete operator of array in JavaScript
delete operator is used to delete an element from the array
var arr=[10,20,30,40,50];
document.write(arr+"<br><br>"); //display array before delete operator
delete arr[1];
document.write(arr); //display array after delete operator
Output:
The code above will display :
10,,30,40,50
array push() method in JavaScript
The push() method adds an element at the end of array
var arr=[10,20,30,40,50];
document.write(arr+"<br><br>"); //displaying array before push method
arr.push(60);
document.write(arr); //displaying array after push method
Output:
The code above will display :
10,20,30,40,50,60
array pop() method in JavaScript
The pop() method removes the last element of the array
var arr=[10,20,30,40,50];
document.write(arr+"<br><br>"); //displaying array before pop method
arr.pop();
document.write(arr); //displaying array after pop method
Output:
The code above will display :
10,20,30,40
array shift() method in JavaScript
The shift() method removes the first array element and "shifts" all other elements to a lower index.
var arr=[10,20,30,40,50];
document.write(arr+"<br><br>"); //displaying array before shift() method
arr.shift();
document.write(arr);//displaying array after shift() method
Output:
The code above will display :
20,30,40,50
array unshift() method in JavaScript
The unshift() method adds a new element to an array (at the beginning), and "unshifts" older elements. The unshift() method returns the new array length.
var arr=[10,20,30,40,50];
document.write(arr+"<br><br>"); //displaying array before unshift()
arr.unshift(5);
document.write(arr); //displaying array after unshift() method
Output:
The code above will display :
5,10,20,30,40,50
array toString() method in JavaScript
The toString() method returns an array as a comma separated string:
var courses=["HTML","CSS","JAVASCRIPT"];
courses.toString();
document.write(courses);
Output:
The code above will display :
array splice() method in JavaScript
The splice() method can be used to add new items to an array:
var courses=["HTML","CSS","JAVASCRIPT"];
courses.splice(2,1,"JAVA","PHP");
document.write(courses);
The first parameter (2) defines the position where new elements should be added (spliced in).
The second parameter (1) defines how many elements should be removed after given position
The rest of the parameters ("JAVA" , "PHP") define the new elements to be added.
The splice() method returns an array with the deleted items:
Output:
The code above will display :
array concat() method in JavaScript
The concat() method creates a new array by merging (concatenating) existing arrays:
The concat() method does not change the existing arrays. It always returns a new array.
var programming=["C","C++","JAVA"];
var web=["HTML","CSS","JAVASCRIPT"];
var courses=programming.concat(web);
document.write(courses);
Output:
The code above will display :
array slice() method in JavaScript
The slice() method slices out a piece of an array into a new array.
The slice() method creates a new array. It does not remove any elements from the source array.
var courses=["C","C++","JAVA","HTML","CSS","JAVASCRIPT"];
var newcourses=courses.slice(3);
document.write(newcourses);
Output:
The code above will display :
array sort() method in JavaScript
The sort() method sorts an array alphabetically:
var courses=["HTML","CSS","JAVASCRIPT"];
courses.sort();
document.write(courses);
Output:
The code above will display :
array reverse() method in JavaScript
The reverse() method reverses the elements in an array.
We can also use it to sort array in descending order
var courses=["HTML","CSS","JAVASCRIPT"];
courses.reverse();
document.write(courses);
Output:
The code above will display :