Cheatsheet

Cheatsheets / Learn JavaScript

Introduction​

 

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Cheatsheets / Learn JavaScript

Conditionals​

 

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VARIABLES
Review Variables
Nice work! This lesson introduced you to variables, a powerful concept you will use in all your future programming endeavors.
Let’s review what we learned:

• Variables hold reusable data in a program and associate it with a name.
• Variables are stored in memory.
• The var keyword is used in pre-ES6 versions of JS.
• let is the preferred way to declare a variable when it can be reassigned, and const is the preferred way to declare a variable with a constant value.
• Variables that have not been initialized store the primitive data type undefined.
• Mathematical assignment operators make it easy to calculate a new value and assign it to the same variable.
• The + operator is used to concatenate strings including string values held in variables
• In ES6, template literals use backticks ` and ${} to interpolate values into a string.
• The typeof keyword returns the data type (as a string) of a value.

Instructions​

To learn more about variables take on these challenges!

• Create variables and manipulate the values
• Check what happens when you try concatenating strings using variables of different data types
• Interpolate multiple variables into a string
• See what happens when you use console.log() on variables declared by different keywords (const, let, var) before they’re defined. For example:

console.log(test1);


const test1 = 'figuring out quirks';

• Find the data type of a variable’s value using the typeof keyword on a variable.
• Use typeof to find the data type of the resulting value when you concatenate variables containing two different data types.