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Defining Variables with let and const

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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.

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    [SOUND] 0:00
    [MUSIC] 0:01
    [SOUND] >> Hello world, Andrew here. 0:03
    Lifelong learner, and JavaScript teacher here at Treehouse. 0:06
    For most of JavaScripts life, there's been only one way to create or 0:10
    declare a variable. 0:14
    Using the var keyword. 0:16
    Most JavaScript programmers learned this method, and 0:18
    a lot still use the var keyword. 0:21
    But some of the behaviors from using var can be problematic or unexpected. 0:22
    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 ES2015, or 0:35
    ECMAScript 2015, introduced two new keywords, const and let. 0:40
    In this workshop, I'll show you how const and let work, and 0:45
    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 1:00
    let, followed by the name of the variable, an equal sign and 1:03
    a value you want to put into that variable. 1:08
    So, when should you use const, and when should you use let? 1:12
    Great questions. 1:15
    I'll answer them in the next few videos. 1:16

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