Variables (JavaScript)

  VARIABLES Mathematical Assignment Operators Let’s consider how we can use variables and math operators to calculate new values and assign them to a variable. Check out the example below: let w =  4 ; w =  w +  1 ; console . log ( w ); // Output: 5 In the example above, we created the variable  w  with the number  4  assigned to it. The following line,  w = w + 1 , increases the value of  w  from  4  to  5 . Another way we could have reassigned  w  after performing some mathematical operation on it is to use built-in  mathematical assignment operators . We could re-write the code above to be: let w =  4 ; w += 1 ; console . log ( w ); // Output: 5 In the second example, we used the  +=  assignment operator to reassign  w . We’re performing the mathematical operation of the first operator  +  using the number to the right, then reassigning  w  to the comput...

  VARIABLES Create a Variable: const The  const  keyword was also introduced in ES6, and is short for the word constant. Just like with  var  and  let  you can store any value in a  const  variable. The way you declare a  const  variable and assign a value to it follows the same structure as  let  and  var . Take a look at the following example: const myName =  'Gilberto' ; console . log ( myName ); // Output: Gilberto However, a  const  variable cannot be reassigned because it is  constant . If you try to reassign a  const  variable, you’ll get a  TypeError . Constant variables  must  be assigned a value when declared. If you try to declare a  const  variable without a value, you’ll get a  SyntaxError . If you’re trying to decide between which keyword to use,  let  or  const , think about whether you’ll need to reassign the variable later on....

  VARIABLES Create a Variable: let As mentioned in the previous exercise, the  let  keyword was introduced in ES6. The  let  keyword signals that the variable can be reassigned a different value. Take a look at the example: let meal =  'Enchiladas' ; console . log ( meal ); // Output: Enchiladas meal =  'Burrito' ; console . log ( meal ); // Output: Burrito Another concept that we should be aware of when using  let  (and even  var ) is that we can declare a variable without assigning the variable a value. In such a case, the variable will be automatically initialized with a value of  undefined : let price ; console . log ( price ); // Output: undefined price =  350 ; console . log ( price ); // Output: 350 Notice in the example above: If we don’t assign a value to a variable declared using the  let  keyword, it automatically has a value of  undefined . We can reassign the value of the variable. Instructions: 1...

  VARIABLES Create a Variable: var There were a lot of changes introduced in the ES6 version of JavaScript in 2015. One of the biggest changes was two new keywords,  let  and  const , to create, or  declare , variables. Prior to the ES6, programmers could only use the  var  keyword to declare variables. var myName =  'Arya' ; console . log ( myName ); // Output: Arya Let’s consider the example above: var , short for variable, is a JavaScript  keyword  that creates, or  declares , a new variable. myName  is the variable’s name. Capitalizing in this way is a standard convention in JavaScript called  camel casing . In camel casing you group words into one, the first word is lowercase, then every word that follows will have its first letter uppercased. (e.g. camelCaseEverything). =  is the  assignment operator . It assigns the value ( 'Arya' ) to the variable ( myName ). 'Arya'  is the  value  assigne...

  VARIABLES Variables In programming, a  variable  is a container for a value. You can think of variables as little containers for information that live in a computer’s memory. Information stored in variables, such as a username, account number, or even personalized greeting can then be found in memory. Variables also provide a way of labeling data with a descriptive name, so our programs can be understood more clearly by the reader and ourselves. In short, variables label and store data in memory. There are only a few things you can do with variables: Create a variable with a descriptive name. Store or update information stored in a variable. Reference or “get” information stored in a variable. It is important to distinguish that variables are not values; they contain values and represent them with a name. Observe the diagram with the colored boxes. Each box represents variables; the values are represented by the content, and the name is represented with the label. In th...