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Getting Started With ES2015

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Declaring Variables in JavaScript

1:20 with Andrew Chalkley

Let's review the original way to declare a variable and how that differs with the modern let and const keywords.

[MUSIC] 0:00
Hello world, Andrew here, lifelong learner and JavaScript teacher here at Treehouse. 0:04
For most of JavaScript's life, there's been only one way to create or 0:10
declare a variable, using the var keyword. 0:14
Most JavaScript programmers learned this method and 0:18
a lot still use the var keyword, but 0:21
some of the behaviors from using var can be problematic or unexpected. 0:23
That's why developers of the JavaScript programming language 0:28
decided to introduce new ways for creating variables. 0:31
The sixth version of JavaScript called ES 2015 or 0:35
ECMAScript 2015, introduce two new keywords. 0:40
Const and let. 0:44
In this workshop, I'll show you how const and let work. 0:46
And explain why you'll want to use them instead of var, when declaring variables. 0:49
But first, 0:54
I just want to mention that const and let work in a similar way to var. 0:55
In each case, you use the keyword var, const, or let. 1:00
Followed by the name of the variable, an equal sign and 1:05
the value you want to put into that variable. 1:09
So, when should you use const and when should you use let? 1:12
Great questions. 1:16
I'll answer them in the next few videos. 1:17