JavaScript Array

In the tutorial, JavaSampleApproach will introduce one of the most important data structures of JavaScript – JavaScript Array.

To practice with JavaScript, we use Browser Console, by open a new browser tab then pressing F12.
1. What is JavaScript Array

JavaScript Array is a structure collection like List. It is used to store multiple objects.

2. How to initial an Array

– method 1: var customers = [];
– method 2: var browsers = ["Chrome", "Safari", "Internet Explorer", "Firefox"];
– method 3: use new Array() such as var subjects = new Array("Mathematics", "Compter");

javascript array - initial values

Note: for practicing, we do NOT use new Array() to initial an array. Because it is NOT clearly, and slowly for performance.

3. Array size

We can use length property to get the size of an Array:

javascript array - size

4. Access Array element

Array uses index number to access element.

javascript array - access elements

5. Add or Remove element

For adding a new element, we can use push() method or use length property:

javascript array - add elements

To remove an element, we use pop() method:

javascript array - pop methods

6. Iterating through Array

To loop an Array, we use for statement:

javascript array - loop

7. toString

We can converts an array to a comma separated string with toString() method:

javascript array - toString

8. Array vs Object

Type of JavaScript Array is object:

javascript array - typeof

-> What is the difference between JavaScript Array vs JavaScript Object?
With JavaScript:

  • arrays use numbered indexes.
  • objects use named indexes.

javascript array - object vs array

9. Recognize an Array

To recognize a JavaScript Array, we use Array.isArray(customers) or customers instanceof Array:

javascript array - recognize an js array

10. Mix multiple types

JavaScript Array can contain multiple elements with difference types, such as String, Number, Boolean, Date, Array and Object.

javascript array - mix type values

By JavaSampleApproach | November 16, 2017.


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