- Regular variables are great for storing numbers, strings, and other single items. But what do you do if you have several related items and you want to store them all at the same time like a list of things. For that we have a special type of variable called an array. The array is one of the cornerstones of Java script programming and moving forward you'll see me use arrays in many different ways for different purposes. An array is literally an array where you can store as few or as many items as you like and retrieve one of, some of, or all of those items.
To create an array first create an undefined variable so var pens. Then add the different values to the array using a comma separated list wrapped in square brackets so something like pens equals red, blue, green, orange. This is a shorthand for the full command pens equals new array red, blue, green, orange which produces the exact same array.
This long hand tells us an array is an object which we'll talk more about later. One interesting note about arrays each value in the array can be a separate data type so you can mix strings, Booleans, and numbers all you like. Var mixed bag equals the string keys, the number five, the Boolean false, the number 568, and the string one more thing. You can also add arrays within arrays so called multidimensional arrays but that's beyond the scope of our current conversation.
Each of the values added to an array is placed in a separate slot and given an index number. Computer indexes start with zero so the first item has index number zero, the second the number one, and so on. Once the array is created, you can retrieve a specific value from the array based on its index so if you want the value number four in the array you call for fourth pen equals pens and then square brackets three. If you need to change a value in the array you simply refer to its index position and assign a new value.
Pens square brackets three equals purple.
Author
Updated
4/1/2019Released
5/17/2017Through practical examples and mini-projects, this course helps you build your understanding of JavaScript piece by piece, from core principles like variables, data types, conditionals, and functions through advanced topics including loops, closures, and DOM scripting. Along the way, you will also be introduced to some ES6 and the basics of JavaScript libraries.
- What is JavaScript?
- Working with data
- Using functions and objects
- Working with JavaScript and the DOM
- Changing DOM elements
- Handling events
- Working with loops
- Making images responsive using markup
- Troubleshooting code
- Validating functionality
- Minifying JavaScript
Skill Level Beginner
Duration
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Introduction
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Welcome1m 7s
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1. JavaScript: An Introduction
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What is JavaScript?2m 38s
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2. The Basics
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Introducing the browser console10m 31s
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3. Working with data
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Data types in JavaScript4m 2s
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Arrays2m 20s
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4. Functions and Objects
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Functions in JavaScript3m 28s
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Build a basic function3m 29s
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Anonymous functions5m 11s
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Variable scope3m 17s
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ES2015: let and const6m 12s
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Make sense of objects3m 19s
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Object constructors6m 16s
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Closures8m 11s
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5. JavaScript and the DOM, Part 1: Changing DOM Elements
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Access and change elements4m 33s
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Access and change classes3m 45s
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Access and change attributes4m 53s
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Add DOM elements6m 56s
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6. Project: Create an Analog Clock
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Use CSS to move clock hands3m 49s
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7. JavaScript and the DOM, Part 2: Events
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What are DOM events?1m 31s
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Some typical DOM events1m 59s
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Add and use event listeners6m 51s
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8. Project: Typing Speed Tester
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Rundown of HTML markup2m 58s
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Build a count-up timer5m 56s
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Add a reset button5m 3s
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9. Loops
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Loops3m 37s
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Looping through arrays4m 7s
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Break and continue loops7m 9s
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10. Project: Automated Responsive Images Markup
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Project breakdown1m 55s
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Rundown of project setup3m 26s
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11. Troubleshooting, Validating, and Minifying JavaScript
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Troubleshooting JavaScript7m 20s
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Online script linting5m 57s
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Automate script linting8m 24s
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Online script minification2m 50s
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Automate script minification2m 24s
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12. Bonus Chapter: Ask the Instructor
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What are arrow functions?3m 11s
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What does the % symbol do?3m 47s
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Conclusion
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Next Steps1m 55s
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Video: Arrays